# Engine check



## altimaSE (Mar 28, 2004)

I just installed a new set of headers, NGK spark plugs wires, new denon high performance plugs, new high performance catalytic, new high performance resonator and a high performance muffler + a 2.25 entire exhaust pipeing, also a cold air intake system, also replace the exhaust air sensor.

Here's my question, the engine check light comes only once in a while, especilly high way driving for a certain distance and at a certain rpm "example : 3,000 rpm for 1 hour it comes on ??? not all the time, and once I drop back to 2.500 rpm the light come off, then back over 3,000rpm no more light until a while after", it come back on.

Strange, city driving no problem, it seems the ECU is always ajusting the air mixture according to the RPM or the external air temperature.
The car drives great I mean great "way more power".

Any thaughts


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## Coco (Apr 30, 2002)

If you installed all those things at the same time, then more than likely your O2 sensor went out. May want to get it checked out by a local mechanic first before you head to the dealer. I'm not sure how many miles you have on your car, so I'm not sure if the dealer would honor your warranty (if you still have one) because of all the mods.


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## BlackedOutAltima (Mar 25, 2004)

Yes, the ECU will constantly adjust your fuel mixture, it has to. However, it doesn't just use engine RPM and IAT. There are a myriad of sensors it uses, including the TPS AND your O2 sensor, just to name a few. I agree, take it to a shop and let them hook up their OBD II scanner (if your car is 1996 or newer, otherwise OBD I) and that will tell you if one or both sensors are bad. Or you could buy a scanner for yourself for about $150-200. Actron makes decent units and then you'll have it for any time your light, a friends light or anybody else's CEL comes on. Good luck!!


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