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How to Audit Google Analytics 4 (GA4): Common Issues and Their Impacts on Your Data
Discover essential GA4 audit best practices to ensure accurate tracking, avoid compliance risks, and make data-driven decisions. Learn to address cross-domain issues, session timeouts, consent settings, and more
Hasan Alanam
Manager, Data Solutions
GA4 is a powerful tool for tracking website and app performance, but even minor misconfigurations can cause inaccurate data, compliance risks, and poor decision-making. Regular audits help maintain accuracy and reliability, preventing data discrepancies from compounding over time. This guide covers essential GA4 audit areas, common issues, and their impact on data-driven decisions.
Key Areas to Audit in GA4
👉 Get Napkyn's Free GA4 Audit Checklist
Cross-Domain Tracking
Admin>Data Collection and Modification>Data Streams>Web stream details>Configure Tag Settings>Configure your domains
Ensure that all your domains are included in this list, however, subdomains are not required as they share the same root domain and often use the same cookies for tracking purposes. As well, it is important to verify that the _gl parameter appears in the URL when navigating from one site to another.
Data Impact: The number of sessions would be higher than the user count in reporting because of the session breakage. In addition, attribution will be skewed towards direct traffic.
👉 15 Common GA4 Attribution Challenges and How to Solve Them
Unwanted Referral Traffic
Admin>Data Collection and Modification>Data Streams>Web stream details>Configure Tag Settings>List unwanted referrals
Make sure that you’ve added all external payment gateways to your referral exclusion list.
Data Impact: You might miss the correct purchase attribution.
👉 Session-Level Attribution in GA4 with BigQuery: A Practical Guide
Session Timeout Settings
Admin>Data Collection and Modification>Data Streams>Web stream details>Configure Tag Settings>Adjust session timeout
Session timeout should be based on the industry that the company is in as different businesses have different engagement patterns. A news website may have shorter session durations since users consume content quickly.
Data Impact: If the timeout is too short, it can create multiple sessions for the same user visit, which leads to inflated session counts inaccurately influencing Average Session Duration or Engagement Rate.
Data Retention Settings
Admin>Data Collection and Modification>Data retention
Configure GA4 data retention settings based on business needs. The default retention period is 2 months, but it can be extended to 14 months for standard properties and 50 months for GA360 properties.
Data Impact: Short retention periods limit trend analysis, affecting long-term business insights and marketing strategy evaluation.
Data Collection Settings
Admin>Data Collection and Modification>Data collection
Enable Google Signals - collect additional traffic insights for audience sharing and ads personalization. Additionally, Activate User-ID Collection. You can then link user behavior across sessions and platforms for more accurate analytics.
If you enable User-Provided Data Collection you can use hashed, consented customer data for enhanced audience insights.
Ensure you agree to User Data Collection Acknowledgement to confirm you have the necessary privacy disclosures and rights from your end users for the collection and processing of their data.
Data Impact: Improved audience measurement, better cross-platform tracking, and enhanced conversion accuracy.
User & Session Tracking
Admin>Data Collection and Modification>Data collection
Accurate user and session tracking is foundational to reliable GA4 reporting. Missing User-ID setup, broken cross-domain tracking, or session timeouts, can fragment user journeys and distort key metrics like engagement rates and conversions. Ensuring that session settings, identity spaces (Device ID, User-ID), and cross-domain linking are properly configured is critical to maintaining a complete view of customer behavior across websites and apps. Regular validation helps ensure that each interaction is correctly attributed to the right user and session.
Data Impact: Incomplete or inaccurate user and session tracking results in inflated user counts, broken funnels, and unreliable attribution. This weakens the ability to understand customer journeys, measure marketing effectiveness, and make informed optimization decisions.
User-ID Setup
Admin>Data Collection and Modification>Data collection
User-ID enables GA4 to associate multiple sessions and devices with a single user, providing a more accurate and unified view of customer behavior. Setting up User-ID requires generating and passing a consistent, unique identifier for signed-in users across all platforms. Without proper User-ID implementation, GA4 treats each device or session as a separate user, leading to fragmented reporting and an incomplete understanding of user journeys. It's crucial to configure User-ID early and validate its transmission through DebugView and real-time reports.
Tip: User-ID only works if users are authenticated / logged-in on your website.
Data Impact: Missing or incorrect User-ID setup results in inflated user counts, inaccurate attribution, and gaps in cross-device journey tracking. This undermines efforts to personalize experiences, optimize campaigns, and accurately measure customer lifetime value.
Consent and Compliance Settings
Admin>Data Collection and Modification>Consent settings
Ensure that Personally Identifiable Information (PII) is not being collected. Verify GDPR/CCPA compliance, including cookie consent mechanisms. Check the page path/URL for any email addresses or other PII.
Data Impact: Capturing personally identifiable information (PII) outside of the user-provided data features breaches GA’s terms of service, which can lead to suspension and termination of accounts by Google. It also limits your ability to adequately control this data capture in regulatory contexts. Non-compliance with GDPR/CCPA can result in legal penalties.
👉 Google Consent Mode’s Impact on Marketing Platforms: What Advertisers Need to Know
Custom Event Tracking
Admin>Data Display>Events
Check that the custom events are firing and there are no events with zero event counts as well as duplicate events due to inconsistent naming conventions. If there are events with very low event count, please validate that GA4 tags are firing properly via any Tag Management System (eg., GTM). In addition, ensure event parameters are consistently passing correct data.
Data Impact: Inaccurate custom event tracking leads to incorrect business decision-making. Garbage in, garbage out.
E-commerce Event tracking
Admin>Data Display>Events
Missing or incorrect e-commerce event tracking (e.g., add_to_cart, purchase) can result in incomplete revenue and conversion data, making it difficult to measure the effectiveness of your business and your marketing. It is always important to compare purchases and revenues with another source of backend data to ensure accuracy. Also, it’s important to monitor the funnel reports in either the GA4 UI or a custom dashboard to ensure all levels of the funnel - upper, mid, and lower - are working as expected.
Data Impact: Inaccurate e-commerce tracking leads to inaccurate marketing decisions which lead to lost opportunities. Broken e-commerce funnel measurement blocks from funnel optimization or worse, leads to wrong optimization decisions.
👉 Impact of Consent Mode on Reporting and Transaction Data in GA4
👉 Unlock Deeper Product Insights with GA4 Item Scope Parameters
👉 How to Set Up GA4 Ecommerce Tracking
GA4 Debugging
Admin>Data Display>DebugView
DebugView is an essential tool in GA4 for validating event and parameter collection during implementation and testing. It displays a real-time stream of user activity, helping teams ensure that events (e.g., page_view, purchase) are properly configured and firing as expected. Without using DebugView, it becomes difficult to catch tracking errors early, which can lead to gaps in data collection and reporting. DebugView is especially useful for comparing sent event data with what is actually logged in GA4, ensuring reliable measurement across your reporting needs.
Data Impact: Failure to use DebugView during implementation can lead to undetected tracking issues, missing critical event data, and inaccurate reporting. Without early validation, organizations risk basing marketing and business decisions on incomplete or incorrect analytics, leading to ineffective campaigns and reduced ROI.
Duplicate Data Issues
Admin>Data Display>DebugView
Duplicate data issues occur when the same events, pageviews, or conversions are recorded multiple times, often due to incorrect tag setups, misfiring triggers, or multiple configurations running in parallel. These errors inflate key metrics like event counts, revenue, and conversions, leading to misleading reports and poor decision-making. It’s critical to audit your tags regularly, check for multiple GA4 configurations firing on the same page, and use DebugView or Tag Assistant to identify and resolve duplication problems early.
Data Impact: Unresolved duplicate data issues result in overstated performance metrics, broken attribution models, and wasted ad spend. This creates confusion for marketing, sales, and executive teams, ultimately eroding trust in analytics and reducing the impact of data-driven strategies.
Custom Event Tracking
Admin > Data Display > Events or
Reports>Engagement>Events
Custom event tracking in GA4 allows you to capture specific user interactions that aren't automatically collected by default (e.g., video_plays, form_submissions). Setting up custom events ensures you gather the right data to measure unique business goals and user engagement accurately. However, if custom events are misconfigured - such as missing parameters or incorrect naming - it can lead to gaps in reporting and limit your ability to build effective audiences or measure conversions. Regular validation through DebugView and event reports is critical to maintaining clean, actionable custom event data.
Data Impact: Inaccurate or missing custom events can severely restrict insights into user behavior, making it difficult to optimize campaigns, websites, or apps. Poorly implemented custom tracking can result in misinformed decisions and lost opportunities for engagement and conversion improvements.
Custom Dimensions & Metrics
Admin > Data Display > Custom Definitions
Custom dimensions and metrics in GA4 allow you to extend your data collection beyond the standard fields, capturing business-specific information like user types, membership levels, or product ratings. Proper setup is critical; misconfigured or unused custom definitions can clutter your property and cause confusion in reporting. It's important to align custom dimensions and metrics with your measurement strategy and to validate that they are set up correctly as well as registered in the Custom Definition section.
Data Impact: Forgetting to register Custom Dimensions and Metrics in the Custom Definitions section results in missing or incomplete data in reports, making it impossible to segment, filter, or analyze important business attributes, ultimately leading to gaps in insights and less effective decision-making.
Traffic Anomalies & Data Spikes
Reports>Reports Snapshot>Insights>View Insights
Unexpected traffic anomalies or sudden data spikes can significantly distort your analytics, making it difficult to understand true user behavior and marketing effectiveness. Large, unexplained increases in traffic might stem from issues such as bot activity, tracking errors, or campaign misconfigurations. It's important to regularly review traffic sources and validate spikes against backend systems or external benchmarks to determine legitimacy. Monitoring insights and acquisition reports closely helps ensure that traffic trends align with business activities and that anomalies are investigated promptly.
Data Impact: Ignoring traffic anomalies can lead to inflated performance metrics, misattribution of marketing success, and poor budgeting decisions. Without properly identifying and correcting data spikes, organizations risk misallocating resources and basing strategic actions on inaccurate insights.
Addressing 'not set' Issues
Reports>Engagement>Landing Pages or
Reports>Acquisition/User Acquisition or Reports>Acquisition/Traffic Acquisition
The "not set" issue occurs in GA4 reports when Google Analytics cannot attribute a session's source/medium or landing page properly. This often happens due to missing UTM parameters, improper tagging of the campaigns, the redirects that strip parameters, or incomplete configuration of the tracking setup.
Data Impact: It is hard to know which marketing channels are working, which makes it hard to allocate your marketing budget. As well, it is tough to know which pages are performing well or need improvement.
You might end up wasting money on campaigns that aren’t driving results because you don’t have the full picture.
Best Practices for GA4 Audits
Align Audits with Business Goals: Focus on metrics critical for marketing optimization.
Use Debugging Tools: Utilize GA Debugger and Tag Assistant to verify tracking setups.
Establish Regular Audit Cadence: Perform comprehensive audits every six months and monthly checks on key metrics.
Implement Anomaly Detection: Use dashboards with alerts for unexpected data shifts.
Conducting regular GA4 audits ensures accurate data, compliance, and actionable insights, empowering your business to make informed decisions and maximize ROI. For expert assistance with your GA4 audit, contact us today.
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How to Audit Google Analytics 4 (GA4): Common Issues and Their Impacts on Your Data
Discover essential GA4 audit best practices to ensure accurate tracking, avoid compliance risks, and make data-driven decisions. Learn to address cross-domain issues, session timeouts, consent settings, and more
Hasan Alanam
Manager, Data Solutions
GA4 is a powerful tool for tracking website and app performance, but even minor misconfigurations can cause inaccurate data, compliance risks, and poor decision-making. Regular audits help maintain accuracy and reliability, preventing data discrepancies from compounding over time. This guide covers essential GA4 audit areas, common issues, and their impact on data-driven decisions.
Key Areas to Audit in GA4
👉 Get Napkyn's Free GA4 Audit Checklist
Cross-Domain Tracking
Admin>Data Collection and Modification>Data Streams>Web stream details>Configure Tag Settings>Configure your domains
Ensure that all your domains are included in this list, however, subdomains are not required as they share the same root domain and often use the same cookies for tracking purposes. As well, it is important to verify that the _gl parameter appears in the URL when navigating from one site to another.
Data Impact: The number of sessions would be higher than the user count in reporting because of the session breakage. In addition, attribution will be skewed towards direct traffic.
👉 15 Common GA4 Attribution Challenges and How to Solve Them
Unwanted Referral Traffic
Admin>Data Collection and Modification>Data Streams>Web stream details>Configure Tag Settings>List unwanted referrals
Make sure that you’ve added all external payment gateways to your referral exclusion list.
Data Impact: You might miss the correct purchase attribution.
👉 Session-Level Attribution in GA4 with BigQuery: A Practical Guide
Session Timeout Settings
Admin>Data Collection and Modification>Data Streams>Web stream details>Configure Tag Settings>Adjust session timeout
Session timeout should be based on the industry that the company is in as different businesses have different engagement patterns. A news website may have shorter session durations since users consume content quickly.
Data Impact: If the timeout is too short, it can create multiple sessions for the same user visit, which leads to inflated session counts inaccurately influencing Average Session Duration or Engagement Rate.
Data Retention Settings
Admin>Data Collection and Modification>Data retention
Configure GA4 data retention settings based on business needs. The default retention period is 2 months, but it can be extended to 14 months for standard properties and 50 months for GA360 properties.
Data Impact: Short retention periods limit trend analysis, affecting long-term business insights and marketing strategy evaluation.
Data Collection Settings
Admin>Data Collection and Modification>Data collection
Enable Google Signals - collect additional traffic insights for audience sharing and ads personalization. Additionally, Activate User-ID Collection. You can then link user behavior across sessions and platforms for more accurate analytics.
If you enable User-Provided Data Collection you can use hashed, consented customer data for enhanced audience insights.
Ensure you agree to User Data Collection Acknowledgement to confirm you have the necessary privacy disclosures and rights from your end users for the collection and processing of their data.
Data Impact: Improved audience measurement, better cross-platform tracking, and enhanced conversion accuracy.
User & Session Tracking
Admin>Data Collection and Modification>Data collection
Accurate user and session tracking is foundational to reliable GA4 reporting. Missing User-ID setup, broken cross-domain tracking, or session timeouts, can fragment user journeys and distort key metrics like engagement rates and conversions. Ensuring that session settings, identity spaces (Device ID, User-ID), and cross-domain linking are properly configured is critical to maintaining a complete view of customer behavior across websites and apps. Regular validation helps ensure that each interaction is correctly attributed to the right user and session.
Data Impact: Incomplete or inaccurate user and session tracking results in inflated user counts, broken funnels, and unreliable attribution. This weakens the ability to understand customer journeys, measure marketing effectiveness, and make informed optimization decisions.
User-ID Setup
Admin>Data Collection and Modification>Data collection
User-ID enables GA4 to associate multiple sessions and devices with a single user, providing a more accurate and unified view of customer behavior. Setting up User-ID requires generating and passing a consistent, unique identifier for signed-in users across all platforms. Without proper User-ID implementation, GA4 treats each device or session as a separate user, leading to fragmented reporting and an incomplete understanding of user journeys. It's crucial to configure User-ID early and validate its transmission through DebugView and real-time reports.
Tip: User-ID only works if users are authenticated / logged-in on your website.
Data Impact: Missing or incorrect User-ID setup results in inflated user counts, inaccurate attribution, and gaps in cross-device journey tracking. This undermines efforts to personalize experiences, optimize campaigns, and accurately measure customer lifetime value.
Consent and Compliance Settings
Admin>Data Collection and Modification>Consent settings
Ensure that Personally Identifiable Information (PII) is not being collected. Verify GDPR/CCPA compliance, including cookie consent mechanisms. Check the page path/URL for any email addresses or other PII.
Data Impact: Capturing personally identifiable information (PII) outside of the user-provided data features breaches GA’s terms of service, which can lead to suspension and termination of accounts by Google. It also limits your ability to adequately control this data capture in regulatory contexts. Non-compliance with GDPR/CCPA can result in legal penalties.
👉 Google Consent Mode’s Impact on Marketing Platforms: What Advertisers Need to Know
Custom Event Tracking
Admin>Data Display>Events
Check that the custom events are firing and there are no events with zero event counts as well as duplicate events due to inconsistent naming conventions. If there are events with very low event count, please validate that GA4 tags are firing properly via any Tag Management System (eg., GTM). In addition, ensure event parameters are consistently passing correct data.
Data Impact: Inaccurate custom event tracking leads to incorrect business decision-making. Garbage in, garbage out.
E-commerce Event tracking
Admin>Data Display>Events
Missing or incorrect e-commerce event tracking (e.g., add_to_cart, purchase) can result in incomplete revenue and conversion data, making it difficult to measure the effectiveness of your business and your marketing. It is always important to compare purchases and revenues with another source of backend data to ensure accuracy. Also, it’s important to monitor the funnel reports in either the GA4 UI or a custom dashboard to ensure all levels of the funnel - upper, mid, and lower - are working as expected.
Data Impact: Inaccurate e-commerce tracking leads to inaccurate marketing decisions which lead to lost opportunities. Broken e-commerce funnel measurement blocks from funnel optimization or worse, leads to wrong optimization decisions.
👉 Impact of Consent Mode on Reporting and Transaction Data in GA4
👉 Unlock Deeper Product Insights with GA4 Item Scope Parameters
👉 How to Set Up GA4 Ecommerce Tracking
GA4 Debugging
Admin>Data Display>DebugView
DebugView is an essential tool in GA4 for validating event and parameter collection during implementation and testing. It displays a real-time stream of user activity, helping teams ensure that events (e.g., page_view, purchase) are properly configured and firing as expected. Without using DebugView, it becomes difficult to catch tracking errors early, which can lead to gaps in data collection and reporting. DebugView is especially useful for comparing sent event data with what is actually logged in GA4, ensuring reliable measurement across your reporting needs.
Data Impact: Failure to use DebugView during implementation can lead to undetected tracking issues, missing critical event data, and inaccurate reporting. Without early validation, organizations risk basing marketing and business decisions on incomplete or incorrect analytics, leading to ineffective campaigns and reduced ROI.
Duplicate Data Issues
Admin>Data Display>DebugView
Duplicate data issues occur when the same events, pageviews, or conversions are recorded multiple times, often due to incorrect tag setups, misfiring triggers, or multiple configurations running in parallel. These errors inflate key metrics like event counts, revenue, and conversions, leading to misleading reports and poor decision-making. It’s critical to audit your tags regularly, check for multiple GA4 configurations firing on the same page, and use DebugView or Tag Assistant to identify and resolve duplication problems early.
Data Impact: Unresolved duplicate data issues result in overstated performance metrics, broken attribution models, and wasted ad spend. This creates confusion for marketing, sales, and executive teams, ultimately eroding trust in analytics and reducing the impact of data-driven strategies.
Custom Event Tracking
Admin > Data Display > Events or
Reports>Engagement>Events
Custom event tracking in GA4 allows you to capture specific user interactions that aren't automatically collected by default (e.g., video_plays, form_submissions). Setting up custom events ensures you gather the right data to measure unique business goals and user engagement accurately. However, if custom events are misconfigured - such as missing parameters or incorrect naming - it can lead to gaps in reporting and limit your ability to build effective audiences or measure conversions. Regular validation through DebugView and event reports is critical to maintaining clean, actionable custom event data.
Data Impact: Inaccurate or missing custom events can severely restrict insights into user behavior, making it difficult to optimize campaigns, websites, or apps. Poorly implemented custom tracking can result in misinformed decisions and lost opportunities for engagement and conversion improvements.
Custom Dimensions & Metrics
Admin > Data Display > Custom Definitions
Custom dimensions and metrics in GA4 allow you to extend your data collection beyond the standard fields, capturing business-specific information like user types, membership levels, or product ratings. Proper setup is critical; misconfigured or unused custom definitions can clutter your property and cause confusion in reporting. It's important to align custom dimensions and metrics with your measurement strategy and to validate that they are set up correctly as well as registered in the Custom Definition section.
Data Impact: Forgetting to register Custom Dimensions and Metrics in the Custom Definitions section results in missing or incomplete data in reports, making it impossible to segment, filter, or analyze important business attributes, ultimately leading to gaps in insights and less effective decision-making.
Traffic Anomalies & Data Spikes
Reports>Reports Snapshot>Insights>View Insights
Unexpected traffic anomalies or sudden data spikes can significantly distort your analytics, making it difficult to understand true user behavior and marketing effectiveness. Large, unexplained increases in traffic might stem from issues such as bot activity, tracking errors, or campaign misconfigurations. It's important to regularly review traffic sources and validate spikes against backend systems or external benchmarks to determine legitimacy. Monitoring insights and acquisition reports closely helps ensure that traffic trends align with business activities and that anomalies are investigated promptly.
Data Impact: Ignoring traffic anomalies can lead to inflated performance metrics, misattribution of marketing success, and poor budgeting decisions. Without properly identifying and correcting data spikes, organizations risk misallocating resources and basing strategic actions on inaccurate insights.
Addressing 'not set' Issues
Reports>Engagement>Landing Pages or
Reports>Acquisition/User Acquisition or Reports>Acquisition/Traffic Acquisition
The "not set" issue occurs in GA4 reports when Google Analytics cannot attribute a session's source/medium or landing page properly. This often happens due to missing UTM parameters, improper tagging of the campaigns, the redirects that strip parameters, or incomplete configuration of the tracking setup.
Data Impact: It is hard to know which marketing channels are working, which makes it hard to allocate your marketing budget. As well, it is tough to know which pages are performing well or need improvement.
You might end up wasting money on campaigns that aren’t driving results because you don’t have the full picture.
Best Practices for GA4 Audits
Align Audits with Business Goals: Focus on metrics critical for marketing optimization.
Use Debugging Tools: Utilize GA Debugger and Tag Assistant to verify tracking setups.
Establish Regular Audit Cadence: Perform comprehensive audits every six months and monthly checks on key metrics.
Implement Anomaly Detection: Use dashboards with alerts for unexpected data shifts.
Conducting regular GA4 audits ensures accurate data, compliance, and actionable insights, empowering your business to make informed decisions and maximize ROI. For expert assistance with your GA4 audit, contact us today.
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