P1123 and P1125

[s.a.haynes]

I have 1999 Boxster that I have recently purchased from the original owner. It currently has 51K+ miles.

Prior to selling me the vehicle the owner had the 45K service performed on the vehicle (at 50K miles). Soon after the service the CEL came on. He returned it to the shop that did the service and they said "bad gas," and turned the light off.

I then got the car. A month or so after getting the car, I started having issues with the engine, especially on cold starts. The engine would "hesitate" when I applied the gas. Eventually the CEL came on again. I brought it into a shop that has a Porsche specialist and they said that they were receiving a "Throttle Body Potentiometer Fault" code. They calibrated the throttle body, reset the CEL and sent me on my way.

After about a week of driving, the CEL came on again. They said that it was the same code and recommended that the throttle body be replaced. $1200 later I have new throttle body and no more hesitation (you would think you could by a rebuild kit for this that would be significantly cheaper... But that's a different story).

The car is now running fine. However, I am having the problem that the CEL will come on after running the car for a while. I took it back to the shop and they told me that I was getting a O2 sensor fault. They reset the code and sent me on way again. They told me to contact them if the light came back on again. Being that I was getting a little wary about maybe being duped, I purchased a CANOBDII code reader. When the light came back on I plugged in and read that I was getting a P1123 and P1125 fault. Both of which indicate an O2 sensor out-of-range error.

Looking at the FF data indicated that the car was apply a -14.5 adjustment to the fuel trim indicating that the car is running rich. The interesting thing is that this is only happening when the car is at idle (800 RPM). The mechanic also told me this answer (which makes me think they are not pulling my chain).

The next question is how do we fix this? The shop mechanic mentioned the EVAP canister valve opening at idle. I was wondering if it could have something to do with the replacement throttle body.

Any help would be appreciated.

Sean

Edited October 4, 2005 by s.a.haynes

[insite]

this is almost certainly your mass airflow sensor (MAF). what are your bank 1 and bank 2 long term fuel trims?

[RayinVa]

I had the same codes on my 99 last year and had the dealer reset it several times. Got the same deal about throttle sensor and finally replaced the mass air sensor my self. I also got software and a plug to my laptop the read and reset codes my self. the MAF replacement is a easy DIY project. The whole deal cost me less than $200.

[Rolando]

I had the same codes on my 99 last year and had the dealer reset it several times.  Got the same deal about throttle sensor and finally replaced the mass air sensor my self.  I also got software and a plug to my laptop the read and reset codes my self.  the MAF replacement is a easy DIY project.  The whole deal cost me less than $200.

<{POST_SNAPBACK}>

I'm also experiencing CEL problems on my 98, think it is the MAF.

Where did you get the MAF at such a good price? (best price that I can find is $245)

Rolando

[s.a.haynes]

this is almost certainly your mass airflow sensor (MAF).  what are your bank 1 and bank 2 long term fuel trims?

<{POST_SNAPBACK}>

The full data is:

Calculated LOAD 2.3%

Engine Coolant Temp 204degF

STFT Bank 1 -10.1%

LTFT Bank 1 -13.2%

STFT Bank 2 -9.3%

LTFT Bank 2 -14.0%

Engine RPM 800 RPM

Vehicle Speed 0

Hope this helps.