Peugeot 408 Check Engine Light and Fuel Consumption

Hmm, sounds familiar. I've got a 408 as well, though I don't remember the exact year. I had a similar issue a while back with the check engine light and the car seemed to be guzzling gas like crazy. Was that the pre-cat or post-cat O2 sensor that's throwing the code? Knowing which one might help narrow down the possibilities.

I confess, I'm not entirely sure which O2 sensor is the culprit, but the error message points towards the heater circuit. Does that resonate with your experience? And if so, what was your particular outcome?

Yep, the heater circuit thing rings a bell. I messed around with it for a while, but eventually, I had to take it to a workshop. They diagnosed a bad connection. Honestly, messing with the vehicle emissions stuff can be a pain, and I didn't want to risk messing something else up in the exhaust system. Plus, the air-fuel ratio is important, you know?

Appreciate the input! It seems a visit to the mechanic is unavoidable. The diagnosis was indeed a defective cable connection, and the repair set me back 95€. The check engine light is now off, and the fuel consumption is back to normal. Thanks again!