helmutstorm6
Lexus ES Exhaust Treatment Malfunction
Summary of the thread
A 2019 Lexus ES hybrid is experiencing an exhaust treatment malfunction, indicated by a check engine light, rough running, and exhaust fumes. Initially suspected to be low DEF fluid, the issue was later identified as a faulty lambda (oxygen) sensor. Replacing the sensor resolved the problem, eliminating the exhaust leak and smell.
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4 comment(s)
helmutstorm6 (community.author)
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?
williamkaiser5
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.
helmutstorm6 (community.author)
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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LEXUS
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ES
williamkaiser5
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?