Ammonia "cat urine"?
Asked by Naptown86 Mar 11, 2018 at 01:40 PM about the 2004 INFINITI G35 x Sedan AWD
Question type: Maintenance & Repair
I have a problem with my car its driving me
insane. Why does my car smell like cat piss
or ammonia when I'm driving? I roll down
the windows it makes it worse. But it only
Smell's like that when I'm rapidly
accelerating. What can cause this? Its a
automatic sedan. Any ideas please!?
2 Answers
A catalytic converter can smell when it starts to go bad, but that smell is based on hydrogen sulfide, aka "rotten eggs." Most people who complain of an "ammonia" smell find it was due to a grade or brand of gas. Try switching to another grade or brand and see if smell goes away. If you *really* want to get to the bottom of it, take your car to a shop that has an exhaust gas analyzer, it might point to nitrogen as a culprit, versus sulfides, etc. Also, make sure all exhaust related parts are working, like EGR (exhaust gas recirculating), PCV, O2 sensors, no leaks, check for OBD trouble codes.
Yes, the "urine" smell is probably coming from the catalytic converter and is a sulfur (hydrogen sulfide). I would follow the recommendations by KenF, step by step.