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larshofmann27

President O2 sensor issue

I have a 2000 Nissan President with a gasoline engine and about 160k km on the clock. Lately, the check engine light's been popping up, and I've noticed my fuel consumption's gone up a bit. Plugged in an OBD reader and it's showing an error related to the oxygen sensor. I've had a quick look and the cable and plug seem okay, but could still be the culprit, I guess? Anyone else run into this?

4 comment(s)

mara_hofmann85

I had a similar issue with my Nissan (though it's a newer model). Same symptoms: check engine light and guzzling fuel. The O2 sensor error could be a faulty sensor, sure, but did the OBD reader specify which sensor? There are usually a couple, before and after the catalytic converter. Knowing which one will help narrow things down. Also, have you checked for any exhaust leaks? That can mess with the readings too.

larshofmann27 (Author)

Good point about specifying the sensor - I should have mentioned that. It's indicating the pre-cat O2 sensor. I haven't specifically checked for exhaust leaks, but I don't hear anything obvious. Where should I be looking?

mara_hofmann85

Okay, pre-cat sensor. Exhaust leaks can be tricky to spot just by sound. Visually inspect the exhaust manifold and the pipe leading to the catalytic converter for any signs of soot or damage. Honestly, though, given the age of the sensor and the error code, plus your symptoms, it's pretty likely the sensor itself. If the wiring looks good, I'd probably just bite the bullet and replace it. Taking it to a workshop might be the easiest solution and they can properly diagnose it.

larshofmann27 (Author)

Thanks a lot for the advice! I took it to a local garage and you were spot on. They checked the wiring and confirmed it was fine. Replaced the pre-cat O2 sensor and cleared the error code. Runs like a charm now, and fuel consumption is back to normal. Total cost was 95€.

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