Start by checking if the conversion tag actually fires. Use Google Tag Assistant or your browser's developer console to inspect the conversion page and confirm the gtag or Google Tag Manager container loads and triggers the conversion event. If you see no tag activity, the implementation is broken at the code level. In Google Ads, navigate to Tools > Measurement > Conversions and verify your conversion action exists and is set to the correct status (active, not removed). Check the tracking tag type matches what's on your site. If you switched from global site tag to GTM or vice versa without updating the conversion action settings, tracking breaks. Look at the last 7 days of conversion data in the conversion action details; zero conversions with decent traffic usually means a firing issue, not a setup issue. Common GTM mistakes include wrong trigger conditions (fires on all pages instead of just thank-you or confirmation pages), incorrect conversion ID or label in the tag configuration, or the tag being paused. Preview mode in GTM shows exactly which tags fire on which pages. Test a conversion yourself and watch it appear in GTM preview before publishing. Domain and consent problems kill tracking silently. If you recently changed domains or subdomains, the conversion tag might still reference the old domain. Cookie consent tools that block Google tags before user approval will prevent tracking for users who don't consent. Check your consent mode setup if you're in Canada or serving European users. At Ottawa SEO, we rebuild tracking from scratch when clients inherit broken setups. We set a test conversion action, fire it manually, wait 3 hours, and confirm it shows in Google Ads before touching the production conversion actions. If conversions suddenly dropped but traffic is stable, check for recent site changes, GTM publishes, or Google Ads interface changes to conversion settings. Google's conversion diagnostic tool under each conversion action sometimes flags specific issues like tag conflicts or cross-domain problems.