P0120: Throttle/Pedal Position Sensor A Circuit Malfunction

P0120: Throttle/Pedal Position Sensor A Circuit Malfunction

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P0120: Throttle/Pedal Position Sensor A Circuit Malfunction – Here's What You Need to Know

Look - if you're dealing with OBD2 code P0120, you're likely experiencing issues with your vehicle's throttle or pedal position sensor. This sensor is crucial for relaying how far your accelerator pedal is pressed, directly impacting the engine's air-fuel mixture and overall performance. Ignoring it can lead to poor acceleration, stalling, or even a complete loss of power, which nobody wants on the road.

Listen - while it might be tempting to throw a new sensor at the problem, that's not always the solution. Before you start replacing parts, let's dig into the symptoms and diagnostics to pinpoint exactly what's going wrong.

Symptoms

  • Unresponsive throttle when pressing the gas pedal
  • Erratic engine acceleration or deceleration
  • Check Engine Light illuminated
  • Engine stalling or hesitation during acceleration
  • Poor fuel economy
  • Increased engine RPMs without input on the pedal
  • Failure to start or difficulty starting the engine

Diagnostic Order

  1. Inspect the throttle position sensor wiring for damage or corrosion.
  2. Check the voltage at the throttle position sensor connector; should be between 0.5 to 4.5 volts.
  3. Test the resistance of the throttle position sensor; it should be around 2-5 kOhms.
  4. Examine the pedal position sensor for similar voltage and resistance values.
  5. Clear the code and perform a throttle position relearn procedure if applicable.

Common Questions

  • What could cause a P0120 code?

    Faulty throttle position sensor, wiring issues, or a bad engine control module (ECM).

  • Can I still drive my car with a P0120 code?

    It's possible, but you're risking stalling or reduced power. Not recommended.

  • How much does it cost to fix a P0120 code?

    Repairs can range from $100 to $300 depending on parts and labor.

  • Is it safe to replace the throttle position sensor myself?

    Yes, if you're comfortable with basic electrical diagnostics and have the right tools.

  • What happens if I ignore a P0120 code?

    Ignoring it can lead to more severe engine issues and safety concerns.

  • Will a faulty pedal position sensor trigger a P0120?

    Yes, issues with the pedal position sensor can also lead to this code.

  • Can other OBD2 codes appear with P0120?

    Yes, related codes like P0121 and P0122 may show up.

  • How do I reset the check engine light?

    Clearing the code with an OBD2 scanner usually does the trick.

Vehicle-Specific Notes

  • Ford EcoBoost engines (1.5/2.0/2.3/3.5L) often experience wiring harness issues due to heat exposure.
  • Honda K-series (2.0/2.4) can show P0120 when the throttle body needs cleaning.
  • Toyota 2GR-FE V6 may have throttle body gasket leaks affecting sensor readings.
  • GM 2.4 Ecotec engines sometimes require a software update after sensor replacement.
  • GM Vortec 5.3 and 6.0 engines may have issues due to corroded connectors.
  • Hyundai/Kia Theta II (2.0/2.4 GDI) generally have a high failure rate for the throttle position sensor.
  • Chrysler 3.6 Pentastar often has problems with the pedal position sensor wiring.
  • BMW N20/N54/N55 engines can throw a P0120 if the throttle body isn't calibrated properly.
  • Subaru EJ20/FA20 engines may have a faulty connection at the throttle position sensor.
  • Nissan VQ35/VK56 can show P0120 due to unreliable ground connections.

Parts and Cost Ranges

  • Throttle Position Sensor: $50 - $150
  • Pedal Position Sensor: $60 - $120
  • Wiring Harness Repair: $30 - $100
  • Throttle Body Cleaning: $20 - $75

What People Get Wrong

  • Thinking a new sensor will fix the problem without checking wiring first.
  • Ignoring symptoms and continuing to drive the vehicle.
  • Not performing a throttle relearn procedure after repairs.
  • Assuming all OBD2 codes are related when they may be independent issues.

Related Codes

For more insights, check out related codes like P0121, P0122, and P0220. Each of these can point to similar issues within the throttle and pedal systems, and knowing them can save you time and money.

Stop throwing parts at your car. The Mobile Master Mechanic app walks you through the exact diagnostic for YOUR specific VIN - engine, year, trim, even mileage-specific known issues. Free download.

-- Hank, Master Mechanic at Mobile Master Mechanic

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