Oxygen sensor issue Mercedes A Klasse

Sounds familiar! I had a similar issue with my Mercedes C Klasse. The check engine light was on, and it turned out to be the oxygen sensor as well. My fuel consumption went up too. Before you replace the sensor, have you tried testing it with a multimeter? It could be a bad connection somewhere. Did you clear the error code after checking the connections? Sometimes the light stays on even after you've fixed the initial problem. Clear the code and see if it comes back. If it does, then it’s probably the oxygen sensor itself.

Thanks for the quick response! I haven't done any sensor testing with a multimeter yet. I'm not super familiar with that, so could you explain the process a little more? I did clear the error code, but it came back on after about 50 km of driving. What values should I be looking for when testing the sensor? I am unsure how to test the cables themselves.

Okay, so the code came back, which confirms it's likely the sensor. As for the multimeter testing, there are tons of tutorials online. Search for 'oxygen sensor testing with multimeter' on your preferred video platform. It's usually about checking the resistance and voltage. But, since you are not familiar with it, and the error code reappeared after you cleared it, my honest advice is to take it to a workshop. They can diagnose it properly and replace the sensor. You might spend more time trying to figure it out yourself, and potentially damage something else.

Thanks, I appreciate the advice! I think you're right, I'll take it to a workshop. They diagnosed it as a faulty oxygen sensor heater circuit. The cable or plug connection of the component was defective, just as the error stated. They quoted me 95€ for the repair, including the sensor and labor. Hopefully, that will sort it out and get my fuel consumption back to normal. Thanks again for your help!