2005 Hyundai Tucson 2.7L - P0122 Fault Code and Transmission Not Upshifting
I own a 2005 Hyundai Tucson with a 2.7L engine, and I'm experiencing a P0122 fault code along with the transmission failing to upshift automatically. I've tested the input signals and confirmed that the battery voltage at the incoming 5V reference is within normal range. Is this behavior typical for the P0122 code, or could it indicate a faulty engine control module (ECM)?
The P0122 code typically relates to an incorrect throttle position sensor (TPS) signal. This can indeed affect transmission shifting behavior. Have you checked for any additional diagnostic trouble codes? Was there recent work performed on the vehicle? At the TPS connector, when unplugged, is Terminal 1 showing 12V on the GRN/BLK wire? If it reads 12V, this may indicate a wiring issue—possibly a short to power—which could be causing incorrect signal readings. In such cases, inspect the harness for damage or grounding problems.