Fuel and air

P1120 — Throttle Position Sensor Out of Range

Severity: medium Drive with care, to a shop

What P1120 means

The engine control unit constantly compares the throttle position sensor (TPS) voltage with what it expects for the commanded throttle angle and pedal position. With P1120, the signal falls outside the allowed range at closed or open throttle, or does not match the command. Wording varies by brand: some mean the throttle sensor, others the pedal sensor circuit or the throttle actuator.

Symptoms

  • Limp mode with limited power and RPM
  • Check Engine light on
  • Hesitation or delay when pressing the accelerator
  • Surging or unstable idle
  • Stalling or hard starting
  • Jerking during acceleration

Possible causes

  1. Failed throttle position sensor
  2. Worn or carbon-fouled throttle body
  3. Damaged wiring or poor connection at the throttle actuator connector
  4. Corroded terminals, open circuit, or short to ground or power
  5. Throttle relearn needed after cleaning or replacement
  6. Faulty accelerator pedal position sensor (on some brands)
  7. Rarely, a faulty ECU

How to diagnose

  1. Scan all codes and freeze frame data, and record them before clearing anything.
  2. Inspect the throttle connector and harness for chafing, corrosion, moisture and a loose plug.
  3. Remove the intake duct and check the throttle plate for carbon buildup, sticking or mechanical wear.
  4. With a scan tool, watch TPS voltage or percent while slowly opening the throttle; it should change smoothly with no jumps or dropouts.
  5. Compare both sensor channels and the pedal sensor readings if the car has them.
  6. Use a multimeter to check the 5 V reference, ground and signal wire continuity against the wiring diagram.
  7. After cleaning or replacing parts, perform a throttle relearn and road test.

Common fixes

  • Clean the throttle body and perform a throttle relearn
  • Replace the throttle position sensor or the whole throttle body assembly
  • Repair the harness or replace a damaged connector
  • Replace the accelerator pedal sensor if it is the faulty part
  • Update ECU software where the manufacturer provides it

P1120 on different brands

Alfa Romeo
Treated as a malfunction of the throttle control unit.
Chevrolet · manuals
Malfunction in the circuit of throttle motor position sensor 1.
Chrysler
Fault in the Throttle Position (TP) sensor 1 circuit.
Ford · manuals
The throttle position value is outside the valid range.
Honda · manuals
Malfunction in the circuit of throttle motor position sensor 1.
Hyundai · manuals
Malfunction of the electronic governor (electronic throttle control).
Land Rover
Throttle position sensor behavior is implausible for current operating conditions (range/performance).
Lexus · manuals
Malfunction in the accelerator pedal position (APP) sensor circuit.

Questions and answers

Can I drive with a P1120 code?

Only briefly and carefully, for example to a shop. The car may enter limp mode and lose power at a bad moment.

Will cleaning the throttle body fix P1120?

Sometimes, if carbon buildup or sticking is the cause. A throttle relearn is needed afterward or the idle may stay unstable.

What most often causes P1120?

A worn throttle position sensor or a poor connection at its connector. Check the wiring and the sensor signal with a scan tool before replacing parts.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.