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2009 Mazda3, P2128

Hey, all. First time back here with the new community…I used to post somewhat regularly back about 4 years ago but I’ve been gone a while. My 2009 Mazda3 is giving me a headache and I thought I would see what advice you guys have.

This was me:

Right before my car went out of warranty, I had a check engine light with trouble code P2128, accelerator position pedal (APP) sensor 2, high voltage. I took it to the dealer, they couldn’t/wouldn’t fix it and told me that if it happened again they’d cover it under warranty. Well it didn’t happen again for 13 months, and guess what, the dealer said they wouldn’t look at the car without a $100 diagnostic fee, which would only be refundable if they decided to cover it under the now expired warranty. Oh, and didn’t I know that they would only extend my warranty 12 months from the original trip in? I was out of luck, and I felt lied to, at least by omission of that important timeframe, at my first visit, so I won’t be returning to the dealer.

I decided to see if it continued to be a problem before I took the car in. No new codes for 8 months, and then it happened again this morning. When this code triggers the check engine light, it puts the car into limp mode, so we drove it around the block and were able to clear the code. I drove to work with no problems.

I’m wondering:

  1. Whether I should try just replacing the sensor since the dealer checked the wiring for problems initially;
  2. How to do that, such as where it’s located; and
  3. Any ballpark costs/number of book hours for parts and repairs at an independent mechanic?

If this is a matter of replacing the accelerator pedal, is that something I can do myself?

That sensor is usually mounted onto the accelerator pedal and not difficult to replace on most cars but I’m not all that familiar with Mazdas.

Why not get the service manual to your car on ebay and follow its procedure.
Very often you can get a cheap CD copy of the actual service manual for $5 or so on ebay.

Edit: here’s one -

I found a service manual online and it doesn’t look too bad. I think I’ll price it out.

If anyone has knowledge of Mazdas specifically, please let me know.

Back for an update: After having this problem more frequently until finally I couldn’t get the code to clear at all, I wound up having the accelerator pedal replaced (Mazda doesn’t sell the sensor separately). It was $200 for the part, plus an hour of labor. So far so good, but it’s only been a few days.

I called the other Mazda dealership in town and ended up having them do the work. It’s freezing here and I don’t have the time or garage space to do it myself, so I was going to take the car somewhere. I decided to skip the $100 diagnostic fee and just had them replace the part directly - hopefully this really was the correct fix!

I’m planning to write a polite letter to Mazda USA to ask them to cover the repair under warranty or maybe split it. I doubt it will go anywhere, though.