Ok this problem has been annoying me for a while, took it to the dealer twice since it's still under warranty. So first time it came up with P0171 emissions code. I took my CAI and took it to the dealer. They looked up the TSB and updated the ECU firmware. 2 days later, same thing and same code. I make an appointment but the next day the light goes away?!? A day later comes back on again.. And kept doing that. Luckily what I came for my appt the light was on. The dealer ended up changing out my injectors. Two weeks go by everything is cool. Then today, light comes on again?!? This time though, no code came up on the navi screen and no performance loss so far. Any ideas guys???

 

I'd guess O2 sensor, but I think are specific codes for O2 faults.

 

Well, took it to the dealer and guess what? "we couldn't find any problems". There are no codes in the system, and the light unfortunately went off when I got to the dealership. On my way home it came on again. I noticed that after spirited driving, the light comes on the next time you start the car, drive it normally for a bit and after a few starts it goes away. I don't even know now, seems like could be something with electronics?

 

I would start with the primary O2 sensor bank 1, clean with contact cleaner or replace and give it a try. The dealer should be able to drive the car and see if the feedback is within specs.

 

A few times I had check engine light come on after a highway ride, when I came to the first red light stop and the engine was just idling. One dealership replaced a coil and reset the light. A month or so later it happened again. Another dealership read the codes- (mistiming) and could not reproduce it so they reset the light and sent me home. Then it started happening more often. But the light would go away if I didn't go to the dealership right away. So I took it to yet another dealership that came highly recommended of this forum and they kept the car for a few days, ran more tests and found that one or two of the cylinders didn't have proper compression readings. They ended up replacing the cylinder head under warranty after getting it approved by Acura- even though the car was already 4.5 years old. I guess the fact that I had these symptoms on record since the car was still under warranty helped. Anyway, I now only take my car to that dealership- it's 60 miles away, but well worth the time and money.

 

My car was doing that for about two days right after I bought it, the techs went thru their protcol and came to the step for a valve adjustment, that solved the problem, check engine light hasn't come back on. (knock on wood...haha)

 

I have the same problem.

 

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I would blame the O2 sensor as well....and the lower one....

 

My '04 NBP 6MT that I traded in did this exact same thing. McDaniels Acura started by replacing ALL of my fuel injectors (woohoo!) for free. A week later, spits out the same CEL (I had slightly different codes, I believe...been a while). My codes told me I was running lean on bank 1 and 2, when I had zero loss in power. Like you, my CEL light flicked on an off, and I often couldn't replicate it with the dealer because it was off by the time I arrived. So I started taking videos with my phone to prove it. I took it back (thankfully it was on when I get there), showed them the pictures and my car, they replaced some O2 sensors and the next 3 years went by without any lights thrown whatsoever.

 

Funny the light went off again today. It comes on (no code) and then 2 days later it turns off. Annoying.

 

Had this same problem ,engine light would turn on every month for two days than go off dealer changed the purge valve ,haven't had a problem yet

 

Hmm this has been happening to me for the past few months. No loss in power, gas milage or really anything. A code only popped up on the navi once.