BladeMD

My 2011 Turbo has about 94k miles on it.... just had the Alarm Siren replaced, oil changed, and new tires and TPMS installed about 500 miles ago....

I’m driving down the highway at 73mph, and all of a sudden I get the check engine light, engine power reduced, PCM failure, and Auto stop/start disabled. I have less high end throttle, but I am able to maintain about 70MPH the rest of the 30 miles home... stop at gas station, get gas.... car restarts with same error messages but will allow me to get up to traffic speeds, so I head to local autoparts store to borrow their OBD reader.

I get the following:

P2138: Throttle/Pedal Position Sensor/Switch “D”/“E” Voltage correlation (DTC severity 2 of 3: Repair immediately)
P2121 Throttle/Pedal Position Sensor “D” Circuit Range/Performance
U0402: Invalid Data from Transmission Control Module
P2100: Throttle Actuator Control Motor Circuit/Open
P1517: Unknown Code


When I start up to leave the Auto Parts store, I’m in complete slug mode.... cant go much faster than 10mph, and it wont go above 1500RPM, and was swapping back n forth between 1st and 2nd gear.

Throttle body replacement might be what I need also after doing a search for the codes above, but nothing Ive found in the searches has confirmed that.

This thread was the closest I could get, but the symptoms were very different, and the codes were not quite the same: https://rennlist.com/forums/cayenne-...-obd-code.html

Any guidance/suggestions would be greatly appreciated!

deilenberger

My first suggestion is to get the codes read with a Porsche specific code reader. Any code > P1000 is a manufacturer specific code. These aren't universal codes - so the usual OBD-II code reader really isn't telling you what the car thinks is wrong.

IF I made a WAG - and that's all it would be with the limited info here - P2138 appears to point to a failing throttle pedal assembly. The pedal assembly has two sensors in it - and it compares one against the other to determine if the primary one is performing correctly. The message you're receiving in P2138 and P2121 is - one of the sensors is going bad. A good Porsche specific code reader should also be able to read the values of both throttle sensors - so you can see if they aren't tracking correctly. The other codes could well be caused by the ECU rejecting the information from the pedal assembly.

That's only a WAG. I'd want to see what something like a PIWIS, Durametric, iCarScan has to say when they read the codes and the output values from the sensors.

BladeMD

Thanks for reply, Don! It appears I can get a iCarSoft from Amazon within a few days... i just cant tell if there is any difference between the POR II version and the POR V2.0... they have slightly differing hardware appearances, but are roughly the same price. Would you (or anyone else) be able to recommend one version over the other?

deilenberger

Hi Doc,

I suggested iCarScan which is similar in functionality. I haven't tried either iCarSoft product - but I know people here will. You might post a new thread asking for reviews of it.

Libast

Any updates on this? My 09 CTTS did the same damn thing today but also threw a cylinder 6 misfire

Libast

Update, I fixed mine- my throttle body butterfly valve was gunked up-- i had changed my oil and unhooked the driver side charge tube, and finding a bunch of oil, i sprayed some cleaner, which sent some what i can best describe as tar into the butterfly valve of the TB, which kept it from closing fully.

Slickdvl

Could be anything - I had a bunch of failures after the e81 swap and thought it was the new throttle body - turned out to be a faulty brand new ignition coil.
have you checked to make sure your ypipe/plenum is in one piece still? Also when was the last time you checked your diverted valves - both are common and known issues at this mileage.