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P1120
System
Powertrain (Engine)
Scanner required
Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Throttle Position Sensor Out of Range

Understand P1120, common causes, and the right TOPDON scanner to diagnose it.

TPS signal out of expected range at closed or open throttle.

Common symptoms

  • Limp mode
  • Hesitation
  • Idle surge

Typical causes

  • Failed throttle position sensor
  • Throttle body wear
  • Wiring at throttle actuator
  • Needs throttle relearn

What scanner do you need?

Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.

Diagnostic tips

  • Record freeze frame data when the code first sets
  • Clear the code only after fixing the root cause
  • Check for related pending codes that point to a common issue
  • Verify battery voltage is above 12.4V before chasing sensor codes

Recommended TOPDON scanners

Frequently asked questions

What does P1120 mean?
P1120 indicates throttle position sensor out of range. TPS signal out of expected range at closed or open throttle.
Can I diagnose P1120 with a basic code reader?
P1120 may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Which TOPDON scanner do I need for P1120?
Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test) See recommended tools on this page.
Is it safe to drive with P1120?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.