Citroen C5 System Readiness Check Error

I had a similar problem with my C5, though I can't remember the build year off the top of my head. Is the error constantly present, or does it disappear after driving for a while? It sounds like your OBD readiness monitors aren't setting. It's like trying to bake a cake before the oven is hot enough; the systems need time to run their self-tests.

Thanks! It's constantly present, even after driving a good bit. What exactly does it mean when the "OBD readiness monitors aren't setting?" Is it something serious?

If the monitors aren't setting, your car will fail its emissions test and vehicle inspection because the onboard diagnostics haven't confirmed that all the emission control systems are working properly. Given that it happened after someone used an OBD2 reader, I would recommend visiting a trusted workshop. They might be able to perform a 'drive cycle' or force the readiness to set, it worked for me.

Took the car to the shop as suggested, and they reset the system readiness. Seems like the previous OBD2 read scrambled things somehow. All good now, and it didn't cost me a thing! Thanks for the advice.