P0120

Throttle position sensor (TPS) circuit malfunction

Detection Conditions

• The signal from the throttle position sensor has fallen below 0.1V or risen above 4.8V after engine start.
• The signal from the throttle position sensor indicates that the throttle opening angle is below 12.5% for 5 seconds (TPS stuck closed) under the following monitoring conditions:
  • Engine coolant temperature is above 80 degrees C
  • MAF sensor signal is above 100 g/s
• The signal from the throttle position sensor indicates that the throttle valve opening angle is above 50% for 5 seconds (TPS stuck open) under the following monitoring conditions :
  • Engine speed above 500 rpm
  • MAF sensor signal below 2.4 g/s

Diagnostic Support Notes

• This is a continuous monitor (CCM)
• Check engine indicator illuminates if the ECU detects the above malfunction condition during the first drive cycle
• PENDING CODE not available
• FREEZE FRAME DATA is available
• DTC is stored in ECU  memory

Possible Causes

• Throttle position sensor malfunction
• Connector or terminal malfunction
• Open circuit between TPS terminal C and ECU
• Short to ground circuit between TPS terminal C and ECU
• Open circuit between TPS terminal B and ECU
• Short to ground circuit between TPS terminal B and ECU
• Open circuit between TPS terminal A and ECU
• Short to reference voltage (Vref) supply circuit between TPS terminal C and ECU
• ECU malfunction
• MAF sensor malfunction
• Electrical corrosion in TPS signal circuit
• Voltage drops in ground circuit or reference voltage (Vref) supply circuit

[P0120 - From 2002 Mazda Millenia factory service manual]