tcossair

iTrader: (2)

The trans am I have came with ORY and O2 sims. However today, I got a service engine soon light and scanned it as:

P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0155 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

From what I read, thats left and right upstream sensors (before the convertor).

Everything seems to run fine, and its the first time the code has shown since I got the car 1200 miles ago.

Is it from the ORY pipe, or do I need new front sensors? (Or possibly another sign I need a PCM tune?)

X-JeSSter

iTrader: (1)

Seems to happen because the o2's get relocated further back and have a hard time staying hot. I've heard Bosch 13111 o2's (rear o2's from a C5) will fix this problem 90% of the time, so I ordered them. I think you can safely ignore the code, maybe even get it disabled in your tune?

tcossair

iTrader: (2)

Thanks, good info, makes sense because of the LT headers. I imagine this might affect some performance/economy though since its the front o2s. I have been getting less than impressive mpg on the highway so far.

X-JeSSter

iTrader: (1)

Well, if your check engine light is on, you're probably running in open loop, and that might effect your mileage a fair amount.

LS1MONSTER

iTrader: (1)

I have the same problem..and it's time for new front 02's. And I have noticed a drop in my gas milage and slight performance loss. I have lazy 02's.

X-JeSSter

iTrader: (1)

If I'm understanding things correctly, the heater circuit code is almost a normal side effect of relocating your o2's another 2 pipe feet away from your heads...

Your MPG and performance losses to speak of may be a bit diminished by your o2's not reading properly, but more than likely the cause is that your check engine light is on and your computer is running in open loop. I might be wrong, though?

tcossair

iTrader: (2)

I was getting <22mpg highway, with no check engine light. Light just came on today and was reset at autozone this morning.

X-JeSSter

iTrader: (1)

Ah, you may be running a bit rich then.

tcossair

iTrader: (2)

Yea, thats my guess too. I'll probably be getting a nice pcm tune within the month if everything goes right, and hopefully that helps some. That and laying off the pedal while around town.

ChaseSS

iTrader: (17)

i melted my O2 extensions once, hopefully you tucked them away from the ORY and LT's

tcossair

iTrader: (2)

Unfortunately the car came that way so I need to check that this weekend.

jmm98LS1

iTrader: (28)

To clear things up a bit:
P0135 and P0155 are the front o2 heater circuit codes. While your front o2 sensors do control fueling in closed loop, throwing these two codes will not cause a performance loss and will not make your car run in open loop. Because the o2's aren't staying as hot, they probably won't be quite as accurate and could cause a minor rich condition, depending on the overall condition of the o2's themselves. As long as you aren't throwing an o2 code for insufficient switching, you can safely ignore the heater codes if you wish. I have tuned them out of my car's pcm so I don't have to stare at that damn SES light anymore.

X-JeSSter

iTrader: (1)

Quick question for you jmm - does P0421 or P0431 (i think these are the exhaust catalyst efficiency below threshhold codes) cause the PCM to go open loop? I believe I scanned my car with a microchips scanner after it threw P0421 and it said the PCM was in open loop, and once I deleted the code, it went back into closed.

jmm98LS1

iTrader: (28)

Not sure about that one....I haven't had cats on my car for over 6 years and deleted all emissions codes a long time ago. My best guess: I really can't see the car going into open loop because a cat went bad. Don't bet any money on that though! Check out the pcm/tuning section.....I'm sure the answer is there somewhere.