P2138 Limp Mode replaced Pedal twice.... CEL on... Help

[BNAS09]

Hi All

I am so frustrated with my car. I have an 08 350z with 62k miles on it. Bought it used and have had the same issue arise over and over and no one seems to know the answer.

What happens is, while I'm driving, all of a sudden the SES light pops up and the car instantly loses power at the pedal. As I pull over and hope the wheel doesn't lock up since the car is quickly decelerating, I'm kicking myself for ever buying the thing. I've taken it to two dealerships. The first reset the code, but issue came back the next day. Second place said it was the after-market wiring done when removing alarm system (some fancy thing the previous owner installed). They said the wires from one of the harnesses was spliced and needed to be replaced... Ok... BTW I've replaced the pedal twice during this time because dealership thought that would work.... It did not....

10 months later, limp mode....always in the middle of the night. Friend did ECU/Pedal relearn and no problems for 2 months... Now car sits because it's in limp mode and SES light remains. I'm so irritated....
If anyone has any ideas, please help

Sincerely,

Sad Z owner.

[BNAS09]

I went to Auto Zone today and code came up as p2138 and he mentioned something about voltage, etc... : /.

Can an unmounted battery have anything to do with it?

[BusyBadger]

Sorry that it's a problem that brought you here.

P2138 is an accelerator pedal position DTC, you said you replaced pedal, did you mean to say the entire pedal assembly (including the position sensor)?

After the second dealership told you the wiring needed to be replaced did you do it?

The Z is drive by wire (instead of a cable directly connected to the throttle), the APP sensor detects the movement of the pedal and signals the ECM that, in turn, controls the throttle. Here's a diagram and some info and even though it's from an '09 Altima it's the same issue.

On a side-note, I'd avoid (at all costs) a dealership that merely cleared a code and took no other diagnostic or corrective action.

Welcome to NICO!

[jerryd1987]

its likely where they spliced the wiring in altered the resistance from the sensor, stuff like that should never be spliced into on a stock ecu since essentially a 5v sensor is nothing more then a adjustable resistor. how much voltage is sent to the ecu is based on output voltage on the sensor, if you change the input voltage or add resistance to the output wire your going to mess up what the ecu sees. either replace the wiring(with oem is what i recommend) or get something like a haltech where you can adjust the 0% and 100% voltage, this is what i had to do to change to cable throttle body(not recommended unless you live in hawaii) and use the pedal sensor as tps.

[BNAS09]

Sorry for such a long, delayed response...

@BusyBadger,
The dealership replaced the pedal assembly as well as replaces one of the two wire harnesses....

Can you recommend a place to order new wiring (better wires??) or should I go through the dealership, again ?
I saw that someone mentioned how horrible the Nissan wires are... I'm starting to think there's a shortage somewhere...