Codes Don’t Fix Problems
Yes, you heard that correct, codes don’t fix problems. Your 'Check Engine' Light (CEL) is on and you run a code scan. It says you have a Throttle Position Sensor (TPS) code, so you replace the TPS and it does not fix the issue. This happens so often and it never surprises me. Let's find out what it takes to throw a code and why that didn’t fix the issue.
Codes are there to help us diagnose issues, but also for the PCM to know what to do it a case there may be an issue at hand. Just because there is a TPS code does not mean there is a TPS sensor problem. Look at the codes deeper. Codes do not fix problems, they send you in direction.
Think about codes like this. You’re working on car- let’s call the car America. America is big, but I need you to get to a very specific address. Codes are trying to do the same for you. Codes are the states. The code description is the town, and the diagnostics of that now get you to the address, or the root cause of your issue. So, to round that up, all the code does basically, is send you in a direction. It says "go look here." Never once did it say, "go replace this part."
After grabbing your code, you know in this case you have a TPS circuit problem. Does the code state an open circuit? Shorted circuit? Low or high voltage? This will send you in another direction. If the code says open circuit, look for the sensor being unplugged, look for breaks in the wiring, or even yes, maybe a bad sensor, but you should check voltage with a meter as instructed by a shop manual. If the codes states a shorted circuit you can do something similar. Look for shorts in the wiring, ways for high voltage to feed back to the PCM, or yes, once again, a bad part.
My intention here is to save you from spending money, throwing parts, and not getting anywhere. Don’t just be a parts changer. Grab data, look at the data, and let it guide you.