P0122 – Throttle/Pedal Position Sensor/Switch A Circuit Low Input: Symptoms, Causes, Diagnosis & Repair Cost (2026 Guide)

P0122

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Overview

The control module stored P0122 because it detected a problem with: Throttle/Pedal Position Sensor/Switch A Circuit Low Input.

P0122 relates to Throttle/Pedal Position Sensor/Switch A Circuit Low Input. Use a quality scan tool, follow wiring diagrams for your vehicle, and confirm tests before replacing expensive parts.

What does the P0122 code mean?

When P0122 is set, the vehicle’s diagnostics detected an issue described as: Throttle/Pedal Position Sensor/Switch A Circuit Low Input. In practice, the ECM/PCM (and related modules) compare sensor inputs, commanded outputs, and self-tests for that subsystem. The exact repair depends on whether the fault is wiring-related, component-related, or a rationality/performance issue for this circuit or system.

Common symptoms of P0122

  • Stalling in some conditions
  • Reduced power
  • Poor throttle response
  • Check engine light
  • Turbo/boost related warnings
  • Surging idle

Possible causes

  • Fault affecting Throttle/Pedal Position Sensor/Switch A Circuit Low Input (wiring, connector, or component)
  • Damaged sensor or actuator internal fault
  • Reference voltage or ground issue
  • Short-to-ground or bias low on the signal circuit
  • Control module or software calibration issue (less common—verify tests first)
  • Past repairs or aftermarket parts causing out-of-spec operation

How to diagnose P0122

  1. Scan for P0122 and review freeze frame / pending codes for related faults
  2. Inspect connectors and wiring related to: Throttle/Pedal Position Sensor/Switch A Circuit Low Input
  3. Compare live data and commanded vs actual values for the affected system (per service information)
  4. Perform circuit tests appropriate to the fault type (continuity, voltage, resistance) before replacing parts
  5. Confirm power and ground integrity at the relevant module or sensor
  6. After repair, clear DTCs and verify under the conditions that originally set P0122

Tip: Use a scan tool that shows live data and freeze frame for the conditions when the code set.

Severity of code P0122

Moderate: Have this code diagnosed soon; ignoring it can lead to worse fuel economy, repeat failures, or secondary damage.

Can you drive with P0122?

Short trips may be okay if the vehicle feels normal, but have it diagnosed—especially if performance, safety warnings, or overheating are present.

Avoid heavy acceleration, towing, or long highway drives until the cause of P0122 is confirmed and repaired.

How to fix it (step-by-step)

  1. Start with visual inspection and connector cleaning/tightening where needed
  2. Confirm failure mode with testing—avoid swapping parts without evidence
  3. Repair wiring or replace the failed component per manufacturer procedure
  4. Clear faults, run relearns if required, and road test to confirm

Repair & fix options

  • Replace failed sensor/actuator if confirmed
  • Verify reference voltage and grounds
  • Locate and repair short-to-ground
  • Clear codes and verify repair with a drive cycle and readiness where applicable
  • Reinspect related monitors if the code returns after repair

Typical repair cost

$100 – $3,200+ depending on cause

Estimated cost breakdown for P0122
Repair type Typical range
Diagnostic And Minor $100 – $450
Common Component Work $150 – $750
Major Subsystem Repair $350 – $2,000
Severe Or Replacement $600 – $3,200+

How to help prevent P0122 in the future

  • Fix new codes early before secondary damage or catalyst stress
  • Keep connectors clean and secure; address rodent or water intrusion in harnesses
  • Use the correct fluids/parts for your vehicle and service intervals
  • Avoid ignoring pending codes after battery work or repairs

When to see a mechanic

Schedule diagnosis if the check engine light is on, drivability is worse, or you notice new noises, smells, or warning lamps. For safety-related (SRS/ABS) or overheating symptoms, prioritize a qualified shop immediately.

Common mistakes when diagnosing P0122

  • Replacing sensors/modules without verifying wiring and reference voltages
  • Ignoring related codes that identify the real root cause
  • Clearing codes without a verification drive cycle

Common vehicles & notes for P0122

  • Ram / Jeep models (common examples—verify for your vehicle)
  • Subaru / GMC applications vary by engine and model year
  • Many other makes—this is a standardized OBD-II definition: Throttle/Pedal Position Sensor/Switch A Circuit Low…

P0122 is reported across many platforms including Ram, Jeep, Subaru, GMC. Always use VIN-specific service information for testing limits and calibration steps.

Frequently asked questions

What does P0122 mean?

P0122 indicates a fault involving Throttle/Pedal Position Sensor/Switch A Circuit Low Input, based on what the control module detected during self-tests or live monitoring.

Is it safe to drive with P0122?

If the vehicle runs normally and no warning lights are flashing, short trips may be reasonable—but avoid ignoring symptoms like misfire, overheating, ABS/SRS warnings, or major loss of power.

How much does it cost to fix P0122?

Typical repairs often fall in the ranges shown on this page, but final cost depends on labor rate, parts quality, and whether the issue is wiring vs. a major component.

What is the most common cause of P0122?

Most shops start with wiring/connectors and the directly monitored component for “Throttle/Pedal Position Sensor/Switch A Circuit Low Input,” then expand testing if the fault returns.

Will P0122 clear itself?

It may become intermittent, but if the underlying fault remains, the code will usually return—especially after a drive cycle.

Can a weak battery cause P0122?

Low system voltage can cause odd sensor/module behavior, but you should still validate the actual DTC and perform normal circuit/component tests.

Related tools

This information is for educational purposes only and is not a substitute for hands-on diagnosis. Always follow manufacturer service information and consult a qualified automotive technician for repairs.