Service Engine Soon???

[Atrivium]

I've had the Service Engine Soon light on since I bought the car a year ago... Do you guys know of any quick fix for these codes? The codes that it gives are 0161 Heated Oxy Sens Heater Circ (Bank 2-Sens 2), 0171 Sys too lean (Bank 1), & 0174 Sys too lean (Bank 2). The car has American Racing LT's & high flow cats to a Borla Exhaust.. I dont know if the SLP Maf Sensor is throwing the codes...

[0rion]

the slp maf isn't doing you any favors for sure....do you still have the stock sensor you could throw on there to see if that takes care of the codes? Other than that...check fuel pressure (58psi at idle) and check for vacuum leaks. Might also check for exhaust leaks that are before your front O2's.

[Atrivium]

I do still have the stock maf sensor, I should try & put it back and see what happens. I've reset the SES light before and it stays off for a while, a day at most and then comes back on... It does have a slight exhaust leak coming from the headers, I think... I havent checked the fuel pressure, its also programmed with a Superchips Power Programmer, but I've programmed it back to stock and still have the same codes, so I put the "Performance" progamming back from the Superchips unit..

[pajeff02]

The rear O2 sender looks like it may have a blown heater circuit. A simple resistance test will tell you if it is in fact bad.

[Atrivium]

Could the blown heater circuit on the rear O2 be causing all 3 codes..? Cause the car runs fine but its just annoying having the SES light on, I hope it would be that easy of a fix..

[pajeff02]

Could the blown heater circuit on the rear O2 be causing all 3 codes..? Cause the car runs fine but its just annoying having the SES light on, I hope it would be that easy of a fix..

The rear O2's simply tell the PCM whether or not the cats are working properly. They have no affect on fueling and whether the car runs lean.

[Atrivium]

I have a feeling that the SLP MAf sensor is making the car run too lean... Cause a couple years ago I had a similar problem with my camaro and it was the stupid maf sensor the whole time... The only bad part it that the SLP MAf sensor still looks brand new.

[pajeff02]

I have a feeling that the SLP MAf sensor is making the car run too lean... Cause a couple years ago I had a similar problem with my camaro and it was the stupid maf sensor the whole time... The only bad part it that the SLP MAf sensor still looks brand new.

Could be the issue. Do you still have the stock MAF?

[Atrivium]

Yeah the guy I bought it from still gave me the stock MAF with the screen and all.. The LT's & High Flow cats wouldnt have anything to do with these codes would they..?

[pajeff02]

Yeah the guy I bought it from still gave me the stock MAF with the screen and all.. The LT's & High Flow cats wouldnt have anything to do with these codes would they..?

To some extent our cars will self tune through feedback from the front O2 senders. An easy check is to look at your short and long term fule trims with a scanner. They should be close to zero, but plus or minus 3-5% is the norm. Modifications that affect airflow, such as the MAF, porting the throttle body, headers and such, have an impact on fueling. If you see trims that are significantly out of whack you know there is an issue.

My guess is that the MAF is your issue, but I would also look for a vacuum leak in the PCV system. Any air introduced into the intake after the MAF will not be accounted for and result in a lean condition. Other possibilities include a clogged fuel filter, low fuel pressure, a loose connection at the throttle body, or an intake leak, just to name a few.

[Atrivium]

To some extent our cars will self tune through feedback from the front O2 senders. An easy check is to look at your short and long term fule trims with a scanner. They should be close to zero, but plus or minus 3-5% is the norm. Modifications that affect airflow, such as the MAF, porting the throttle body, headers and such, have an impact on fueling. If you see trims that are significantly out of whack you know there is an issue.

My guess is that the MAF is your issue, but I would also look for a vacuum leak in the PCV system. Any air introduced into the intake after the MAF will not be accounted for and result in a lean condition. Other possibilities include a clogged fuel filter, low fuel pressure, a loose connection at the throttle body, or an intake leak, just to name a few.

Wow!! Pretty much I'm best off getting the fuel system tested to find out .. Cause the only thing that I've done as far as trying to help the fuel system is: changed out the fuel filter and threw in a Lucas Fuel System cleaner... hoping this wouldve fixed my lean problem, but its been a couple of months since Ive done that and I still have the lean codes and the O2 code.. Then again I bought the car last year and its an '01 TA that had only 48k mi on it.. So it sat a lot I guess, not a daily driver like I have it for (It has 58k mi on it now)...

[Atrivium]

Thanks for all the info guys... appreciate it... time to trying some of these things out and I'll keep you guys posted on the results..

[0rion]

I'd say if you have a header leak that could be the reason for the lean codes. You might not be lean at all though....that will create a false lean and cause the car to dump too much fuel. What does your exhaust tips look like? Sooted up real bad? I would put fixing that header leak at the top of the list.

[1998 T/A]

i got the same exact codes thrown when my fuel pump went bad...low pressure so i changed the pump never had a SES light for over a year after that

[MAXX2]

Thanks for all the info guys... appreciate it... time to trying some of these things out and I'll keep you guys posted on the results..

Yeh, fix the leaks first. If that doesn't turn off the light, do this---

Pull the oxygen sensor behind the cat, and don't touch it with your fingers. Clean it with Copper Cleaner, then soapy water, then clean water. Wait half and hour, again not touching it with your fingers, reinstall it, and fire up the motor. If it works, you now know one of the tricks of the trade or ???

MAXX

[Atrivium]

Well guys its been a long time since I've replied to this post, but I was able to fix my lean codes by replacing the SLP MAF sensor with the original (stock) MAF sensor. The only code Ive had left is the P0161 Heated Oxy Sens Heater Circ (Bank 2-Sens 2). The Check Engine light will come and go some times but this code always comes back. Im hoping its just an 02 sensor, I hope its not the catalytic converter going bad, it looks fairly new.. Does anyone know if this code (P0161) is just a bad 02 sensor or is it most likely a bad catalytic converter..?

[pajeff02]

Sounds like the heater circuit burned out in the sensor -- fairly common issue that can occur on any car really. You can test the heater circuit with a multimeter or DVOM quite easily.

[WILDKARDBOYZ]

why did you say the slp mafs was no good just asking why is there a difference ???

[jaydean21849]

Bad converter just cuz its new don't mean squat

[Smittro]

Go to a reputable tuner and have the rear 02's turned off..