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

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.

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 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.

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.

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.

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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