2007 Mazda 3 Sensor Issue?
 

I have a 2007 Mazda 3 (~185k miles) that recently began having issues. The issues were first noticed when I got in, started it up, and put it in reverse. The reverse gear jerked hard (enough to spill my coffee). I also noticed that when I pressed the accelerator, the car did not rev or accelerate backwards (or forwards in D for that matter). Hadn't changed the fluid in a while, so I completed a drain and fill on it. No help. Checked the OBD codes on the car. Several came back (P0441, P2177, P050A, P0123, P0126, P0128). Still stuck on the transmission, I thought it could be one of the speed sensors on the tranny. But, no P0715 or P0720. May be there and my code reader does not capture TCM codes, not sure.

Then, I started Googling and reading some about the symptoms indicated by the codes. Even though a throttle position sensor was referenced, I cannot find much that says this car even has one, at least not independently that can be serviced/replaced. Thought it could be the MAF. I pulled it out and cleaned it (spray cleaner, no touch/brushing). After re-installing the MAF, the car will not start at all.

I cleared the codes and then scanned again. Only one code, P2135. Indicates throttle/pedal position sensor. Looks like it is behind the gas pedal. I am OK with replacing it if that is what is needed, but it is an expensive part and I would like to be more confident that this is it before spending the money. Makes sense to me that this may be it given the fuel/air mix, injector, intake air, throttle position sensor variety of the original codes I pulled. Also, the non-acceleration when pressing the gas pedal seems to go with the sensor not recognizing the pedal position change.

Anything else I can do to confirm what is wrong here?

Thanks

Mazda 3
 

So the p2135 is a throttle position 1 and 2 Correlation incorrect. This is referring to voltage TPS 1 in in throttle body and tps2 is behind the pedal. However based on description about what the car is doing and the model year and mileage I’m gonna let you know it’s almost certainly a TCM. 99% of the time they do what you described it’s a TCM very common on high mileage Mazda 3 of those similar model years. As far as the not starting after the Maf cleaning could of accidentally damage sensor but it would be a good Idea to remove the air hose and check the throttle body for grime over time it accumulates and restricts air flow. Note I say remove because also accumulates on back fo throttle body and be very careful not to open the flap this can cause serious damage to it.

Thanks. That makes sense with the symptoms I have with the car.
After reading various posts regarding the TCM, what is the best avenue to take for replacement. I have seen options for buying new (expensive), buying refurbished and sending old one in as a core replacement, and sending the current one in for repair. Looks like repair or refurbished is between $200-$300, but not sure how reliable these sources are (anyone had specific experiences with a good one?). New runs $500 and up. More than I would like to put into it since I plan to sell it once I get it back into drive-able condition. A friend had a newer car come available so I have a replacement. I plan to try replace it myself without taking it to a shop.

I have removed the throttle body and cleaned it. Right now, I have a new OEM throttle body on the car in an effort to rule it out as root cause.

Thanks again.