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car stuck in limp mode after pedal position sensor replacement
i just got my car back from getting diagnosed and my mechanic said it needed a new pedal position sensor. but after replacing the sensor the car went into limp mode, after trying to calibrate the new sensor and trying to reset the ecu nothing was working even after spending arounf an hour trying to reset it. since the new sensor wasn’t working i out the old one back on but now the car is stuck in limp mode with no throttle response and the tcs engine light and slip light are all on. i watched every video and read multiple forums and i can’t find anyone with the same problem as me. also the codes the car were giving my mechanic were p2126 and p2127 and i haven’t checked the codes since the car has went into limp mode
Most likely you need to clear stored learned data. This will require a bi-directional scan tool. After the permanent memory is cleared, you can execute the idle relearn or TPS calibration. I just went through a related (but not the same) issue on a 2006 Honda Civic after cleaning the throttle body. The car had a high idle, causing it to roll faster than normal when in drive or reverse (AT). Lots of bad information online about idle relearn procedures and disconnecting the battery. None of these procedures would clear the permanent memory.
Also, make sure you are using an OEM replacement pedal position sensor. You could also have a wiring fault. Was any other work done on the vehicle recently that involved messing with the wiring harness in any way?
. Was any other work done on the vehicle recently that involved messing with the wiring harness in any way?
yeah my car started having a high idle and it would drive like it was in 5th gear (i have an automatic), meaning it would stop at 2500 rpm and take a while picking up speed, i paid a friend to fix a problem in the rear suspension and he ended up replacing all my fuses and “cleaning” my wiring harness idk how or what he did though i wasn’t there when he did any work on it, however now the car won’t even drive after taking off the sensor. also do you know where i can get a tool to fully reset the ecu like you said?
makes some cheaper options (vehicle make specific). I was quoted $200.00 by the dealer to clear the learned data on the 2006 Honda Civic (outrageous price for pushing a few buttons and then doing an idle relearn, 15min all said and done). I always wanted a bi-directional tool since I do a lot of auto-repair and maintenance for the family cars. I splurged a bit and picked up an
. XTOOL is a fairly new Chinese based company. As much as I would have preferred a more established name brand, I simply cannot afford them (Snap-on, Matco, Bosch, Autel, etc). The XTOOL D8 has very similar features but at a much lower price. It's not perfect, but so far it's worked on all the vehicles I have tested it with. It's fast/responsive, and there are software updates pushed almost daily.
Before you run off and purchase an expensive tool. I would sync up with your friend and get a clear idea of what portions of the wiring harness he tinkered with. What fuses were replaced exactly? What connections were cleaned?. It's possible he introduced a fault by accident. I really hope he had the battery disconnected while doing the work, it's very easy to cause a short while disconnecting and cleaning contacts around fuse boxes. If everything looks good, then start the troubleshooting process on the pedal position sensor. Make sure the wiring is good, you will need to find a wiring circuit diagram. I don't see any open circuit codes, which makes me think it's a calibration issue.
You could also have a wiring fault. Was any other work done on the vehicle recently that involved messing with the wiring harness in any way?
I would start here and reference page 550 of Section EC of the factory service manual
They are identifying P2127 as low voltage from sensor circuit #2 and no data is available for P2126 but if your scanner is saying ‘range & performance’ I bet the sensor is operating outside of it’s voltage range (ignition on pressed is between 1.95v and 2.4v and when released .15v and .60v - as measured with a volt meter. If you’re using a OBD2 or Consult the voltages are slightly different).
You can back-pin the connector and push on the pedal and see what your voltage are when the pedal is fully released and fully pressed. This will tell you which direction you need to go.
Pure speculation but if you put the sensor in on the pedal it has a little intentional play and depending on how you clock it on the pedal assembly it and can operate outside the aforementioned voltage ranges and kick the car into limp mode. This could be as simple as a quick remove, adjust, reinstall. Usually if something wrong with supply voltage, grounds, or the sensor you get both sensor #1 codes and sensor #2 codes. If you clocked it too far in one direction than one sensor is out of range while the other is still in range (if any of this makes sense??).
Pages 550 through 555 read pretty easy and it was great background knowledge and reference when I had APP sensor issues.
If you still cant figure it out let us know and we can dive into it a little further
Good info Beall! I have my FSM backed up on another computer while writing my posts, so I haven't been able to reference it. Damn shame Nissan sent out cease and desist letters to the places hosting full copies in pdf. After finding the YT video I linked above, I started thinking along the same lines you mentioned. The pedal sensor being out of range from improper indexing during the install, or possibly one of the bump stops is damaged or missing. This is an odd issue and I don't think I've seen it pop up on the forums before.
-Icer
What about Nico?? They have versions on their site! Ohhhhh boy!
oh yea - I didnt even think about the bump stop … but same net effect.
I dont know if you saw my post about the ‘new pup’ 350z … essentially got it for an amazing price with a bunch of goodies because the owner, his mechanic buddy, and the internetttzzzzzzzz couldnt solve a APP sensor high voltage issue … it took some researching, studying, trouble shooting and I re-made the APP sensor connector to give myself pigtails to hook a volt meter too (and further trouble shoot) and it made the diagnosis and repair pretty easy and straight forward.
08-22-2022, 09:26 AM
car stuck in limp mode after pedal position sensor replacement
