Audi A4 System Readiness Check Issues: Fix Guide

I had a similar issue with my 2016 Audi A3, also with a gasoline engine. Having some experience with car diagnostics, I first thought it was serious, but it turned out to be quite straightforward. The check engine light and system readiness warnings often appear after the battery has been disconnected or after performing onboard diagnostics scans. The car needs to complete several drive cycles to reset these monitors and restore full OBD readiness status. In my case, the workshop confirmed this through diagnostics testing at no cost since I was a regular customer. They explained that modern cars need specific driving conditions to complete their self-tests, especially for the exhaust system monitoring. To reset the readiness monitors, I had to: 1. Drive at various speeds 2. Include some highway driving 3. Let the car idle for periods 4. Complete several cold starts After about 50-100km of normal driving, all monitors cleared themselves. What specific error codes is your A4 showing? Have you had any recent battery work or disconnections? This information would help determine if youre dealing with the same situation or if theres a different underlying issue.

I wanted to update that after my last vehicle inspection at 161709KM, the issue persisted. Following the suggested drive cycle pattern worked partially, but the system readiness check remained incomplete. The workshop ran car diagnostics and found a failing O2 sensor was preventing the computer reset from completing properly. Once replaced, the check engine warnings cleared after a proper drive cycle. Total repair cost was 350 Euro including parts and labor. Much better than initially feared.

Thanks for the follow-up about your O2 sensor repair. This sounds very similar to what happened with my A3 later on, the initial drive cycles werent fully resolving the readiness monitors because of the faulty sensor. Your repair cost of 350 Euro is actually quite reasonable. When my O2 sensor eventually failed, I paid around 380 Euro for a similar fix. Like your case, the emissions test indicators wouldnt reset properly until the sensor was replaced. The important lesson here is that while OBD readiness and drive cycles can often clear warning messages, persistent system readiness check failures usually point to an actual hardware issue needing attention. In both our cases, the O2 sensor was preventing the computer reset from completing successfully. This really highlights how modern engine management systems are quite good at identifying real issues versus temporary glitches. When drive cycles dont resolve the warnings, its typically worth getting professional diagnostics done rather than continuing to attempt resets. Have all your readiness monitors stayed clear since the repair? It typically takes one complete drive cycle after an O2 sensor replacement to restore full system functionality.

Thanks for the advice. I wanted to post a final update: The check engine light has stayed off completely since the O2 sensor replacement. After following a specific drive cycle recommended by the technician, all system readiness monitors are now showing complete status. The car diagnostics confirmed everything is working properly, all emissions test parameters are within normal range. For anyone facing similar issues, dont assume you need major repairs right away. The onboard diagnostics system is quite precise in identifying the root cause, and sometimes its just a single component like in my case. Total repair came to 350 Euro which was fair considering the thorough vehicle inspection and sensor replacement. Much better value than continuing to chase warning lights with temporary fixes. Really glad I got this resolved before my next emissions test. The warning messages were stressful but the actual fix was straightforward once properly diagnosed.