Lexus ES Exhaust Treatment Malfunction

I'm at my wit's end! My 2019 Lexus ES hybrid is giving me fits. The check engine light is on, it's running rough, and I swear I can smell exhaust fumes, maybe even a leak. It's got 185222 km on the clock. I thought maybe it was low on DEF fluid, but that's not it. What could be causing this awful exhaust treatment malfunction?

4 comment(s)

Sounds familiar. I had similar symptoms with my old BMW after its oxygen sensor went bad. Rough running, engine light… the whole shebang. Ever had the oxygen sensor checked?

An oxygen sensor? Could that really cause all these problems? I thought that just affected fuel efficiency, not the exhaust system itself. How did you figure out it was the oxygen sensor on your BMW?

Well, the O2 sensor tells the engine how to burn fuel efficiently, and a bad one can mess up the whole combustion process. Think of it like a chef with a broken thermometer. He might try, but the cake will burn. I didn’t figure it out myself; my mechanic ran a diagnostic. I'd suggest doing the same.

It was the lambda sensor, just like your oxygen sensor! The garage confirmed that the exhaust leak and smell were also consequences of the bad sensor. Repair cost me 375€. I appreciate the help!

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