Throttle Position Circuit Malfunction

Fault ID
P0120

Title
Throttle Position Circuit Malfunction

Background
- The throttle position sensor outputs a voltage which corresponds to the throttle valve opening angle.
- The engine control module checks whether the voltage is within a specified range. In addition, it checks that the voltage output does not become too large while the engine is idling.

Range of Check 1
- Ignition switch: ON
- Excluding 60 seconds after the ignition switch is turned to ON or immediately after the engine starts.

Set Conditions 1
- When the closed throttle position switch is ON, the sensor output voltage is 2 V or more for 4 seconds.

or

- The sensor output voltage is 0.2 V or less for 4 seconds.

Range of Check 2
- Ignition switch: ON
- Excluding 60 seconds after the ignition switch is turned to ON or immediately after the engine starts.
- Engine speed is approx. 500-3,000 r/min.
- During a low load operation.

Set Conditions 2
- The sensor output voltage is over 4.6 V for 10 seconds.

Effect
Limp-in: No increase in fuel injection amount during acceleration due to the unreliable throttle position sensor signal.

Probable causes
- Throttle position sensor failed or maladjusted.
- Open or shorted throttle position sensor circuit, or loose connector.
- Closed throttle position switch ON malfunction.
- Closed throttle position switch signal wire shorted.
- Engine control module failed.