# 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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## Ruben (Oct 15, 2002)

The o2 sensors work with heat, and when they get too hot, a code may get thrown...

What year car is it?


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## KA24Tech (Feb 2, 2004)

It may just be a Catalyst efficiency code. Sometimes when the car is in a long cruise (3000 for an hour) the O2 gets into a slow small voltage wave pattern and on occassion the ECU thinks that this is a problem because it is not seeing the O2 ranging. I would take it to an Auto Zone or put the ECU into diagnostic mode and see what the stored codes are.

Troy


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