TEST 4: TPS Code Won't Go Away
So you've tested the TPS per the instructions in this article and according to the test results, the TPS is good yet the check engine light is still on. Well, here are a couple of suggestions that might inspire your next diagnostic move:
- The throttle plate's idle-stop screw's factory adjustment has been altered so that the engine could be idled up and mask a miss/misfire and/or rough idle. This increases the TP sensor's signal to the PCM. The PCM doesn't like it and lights up the check engine light (CEL).
- The throttle cable is binding and causing the throttle plate to not fully close.
- This can be verified by simply having someone inside the vehicle pushing the accelerator cable to the floor and releasing it, with the engine OFF, while you visually check that the throttle plate and cable are not getting stuck somewhere in their travel.
- The TPS is failing intermittently. Which means that it works fine most of the time, but every now and then it doesn't:
- I have found that the best way to test these intermittents is to road-test the vehicle with the multimeter hooked up to the TP signal wire with a long wire so that I can comfortably observe the signal going up and down as I or someone else drives.
- The TP sensor's connector is bad, usually the locking tab is broken and the connector has worked itself loose, causing an intermittent false connection.
If this info really saved the day, buy me a beer!