P0120

High Severity

Throttle Position Sensor A Circuit

Fuel System

What Does P0120 Mean?

General fault in the TPS circuit. The TPS tells the ECM how far the throttle is open.

Common Fix

Replace TPS or throttle body

Estimated Cost (DIY)

$20 - $150

Symptoms

  • ⚠️Erratic idle
  • ⚠️Hesitation on acceleration
  • ⚠️Surging
  • ⚠️Reduced power mode

Common Causes

Faulty TPSlikely
Corroded TPS connectorpossible
Wiring issuepossible
Worn throttle bodypossible

How to Diagnose P0120

  1. 1Check TPS connector for corrosion
  2. 2Sweep TPS with scan tool — look for dropouts
  3. 3Measure TPS voltage at closed and WOT
  4. 4Replace TPS if erratic

OEM Diagnostic Flowchart

Scroll to load technician if/then branches.

Read live data and freeze frame for P0120 to pinpoint the cause before buying parts.

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Related Resources

Repair guides, symptom pages, and wiring diagrams related to P0120.

OEM Manual Evidence

Browse →
2013 GMC Truck Yukon XL Denali AWD V8-6.2L A L L Diagnostic Trouble Codes ( DTC )OEM Manual

A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL Denali AWD V8-6.2L Service Manual | Operation CHARM Operation CHARM : Car...

2013 GMC Truck Yukon XL Denali 2WD V8-6.2L A L L Diagnostic Trouble Codes ( DTC )OEM Manual

A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL Denali 2WD V8-6.2L Service Manual | Operation CHARM Operation CHARM : Car...

2013 GMC Truck Yukon XL 4WD V8-6.0L A L L Diagnostic Trouble Codes ( DTC )OEM Manual

A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL 4WD V8-6.0L Service Manual | Operation CHARM Operation CHARM : Car repair...

2013 GMC Truck Yukon XL 4WD V8-5.3L A L L Diagnostic Trouble Codes ( DTC )OEM Manual

A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL 4WD V8-5.3L Service Manual | Operation CHARM Operation CHARM : Car repair...

Exact Vehicle Hubs

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2013 Gmc Truck Yukon Xl 4wd V8 5.3l Repair HubManual

Open the exact vehicle hub grounded by OEM manual evidence related to P0120.

2013 Gmc Truck Yukon Xl 4wd V8 6.0l Repair HubManual

Open the exact vehicle hub grounded by OEM manual evidence related to P0120.

2013 Gmc Truck Yukon Xl Denali 2wd V8 6.2l Repair HubManual

Open the exact vehicle hub grounded by OEM manual evidence related to P0120.

2013 Gmc Truck Yukon Xl Denali Awd V8 6.2l Repair HubManual

Open the exact vehicle hub grounded by OEM manual evidence related to P0120.

Related Codes

P0121: Throttle Position Sensor A Range/PerformanceRelated

The TPS reading does not match expected values based on MAP, RPM, and other inputs. Erratic readings indicate a worn TPS.

P0122: Throttle Position Sensor A Circuit LowRelated

TPS voltage is below minimum threshold. The ECM cannot determine throttle position accurately.

P0123: Throttle Position Sensor A Circuit HighRelated

TPS voltage is above maximum expected. ECM sees the throttle as more open than it actually is.

Frequently Asked Questions

Can a dirty throttle body cause P0120?
Yes — carbon buildup can prevent the throttle from closing fully, confusing the TPS. Clean the throttle body first.
What is limp mode?
When the ECM cannot trust the TPS, it limits power to protect the engine. This is called limp mode or reduced power mode.

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