P0122 - Throttle Position Sensor 1 Circuit Low: Notes

Fig 1: Identifying Throttle Position Sensor Wiring Diagram

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Theory of Operation

The Electronic Throttle Control (ETC) system uses two Throttle Position Sensors (TPS) to monitor the throttle blade position. The Throttle Position Sensors 1 and 2 are located within the Throttle Body assembly. Each sensor has a 5-Volt reference circuit, a low reference circuit, and a signal circuit. Processors are also used to monitor the ETC system data. The processors are located within the Powertrain Control Module (PCM). Each signal circuit provides the processors with a signal voltage proportional to throttle blade movement. The processors share and monitor data to verify that the indicated TPS calculation is correct.

>>When Monitored:<< With the ignition on. Battery voltage greater than 10.0 Volts.
>>Set Condition:<< Throttle Position Sensor (TPS) voltage at the Powertrain Control Module (PCM) is less than 0.16 Volt for 0.7 second. One Trip Fault. Three good trips to turn off the MIL. ETC light will illuminate.

Possible Causes
(F855) 5-VOLT SUPPLY CIRCUIT OPEN
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
(K22) TP SENSOR NO. 1 SIGNAL CIRCUIT SHORTED TO GROUND
(K22) TP SENSOR NO. 1 SIGNAL CIRCUIT SHORTED TO THE (K922) TP SENSOR RETURN CIRCUIT
(K22) TP SENSOR NO. 1 SIGNAL CIRCUIT OPEN
THROTTLE POSITION SENSOR/THROTTLE BODY
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to Pre-Diagnostic Troubleshooting Procedure .