P0120 - Throttle Position Sensor Circuit Malfunction in Common Vehicles like Honda and Toyota

Quick Answer

P0120 means: P0120 indicates a malfunction in the throttle position sensor circuit.

Fix: Check and replace faulty components Cost: $150 - $250 Time: 90-180 minutes

Can I drive with P0120? Immediate attention is recommended to avoid drivability issues.

Common Questions

What does P0120 mean and how does it affect my car?

P0120 indicates a problem with the throttle position sensor circuit, which can lead to poor acceleration and stalling. It’s essential to address this to maintain vehicle performance and safety.

What are the most common causes of P0120 and how much does it cost to fix?

Common causes include a faulty throttle position sensor and damaged wiring. Repair costs can range from $150 to $250 for sensor replacement, depending on your vehicle.

Can I drive my car with P0120 or should I stop immediately?

While you may still operate your vehicle, it’s advised to stop driving it until the issue is resolved to prevent further damage and ensure safety.

How can I diagnose P0120 myself using GeekOBD APP?

You can use the GeekOBD APP to scan for codes, view live data from the TPS, and see freeze frame data to help pinpoint the issue.

What vehicles are most commonly affected by P0120?

Commonly affected vehicles include the 2008-2012 Honda Accord and 2010-2015 Toyota Camry, among others. Check for specific recalls related to throttle issues.

How can I prevent P0120 from happening again?

Regular maintenance checks, keeping the throttle body clean, and ensuring all connections are secure can help prevent future issues with the TPS.

What is P0120?

The Diagnostic Trouble Code (DTC) P0120 indicates a malfunction in the throttle position sensor (TPS) circuit. The throttle position sensor is a critical component in electronic throttle control systems, which measure the position of the throttle plate and send this information to the Engine Control Unit (ECU). When the ECU detects a problem in the TPS circuit, such as an out-of-range voltage, it triggers the P0120 code. This can lead to various drivability issues, including poor acceleration, stalling, or even the vehicle going into 'limp mode' to protect the engine. For instance, owners of 2008-2012 Honda Accords or 2010-2015 Toyota Camrys may experience these symptoms due to a faulty TPS or wiring issues. If left unaddressed, it can lead to decreased fuel efficiency and increased emissions. Therefore, understanding the implications of the P0120 code is crucial for maintaining optimal vehicle performance and ensuring your safety on the road.

System: P - Powertrain (Engine, Transmission, Emissions)

Symptoms

Common symptoms when P0120 is present:

  • Check engine light stays on constantly, indicating an issue that needs to be addressed.
  • Engine hesitates during acceleration, which can be dangerous when merging or overtaking.
  • Fuel economy decreased by 10-15%, leading to increased fuel expenses.
  • Rough idling may occur due to improper air-fuel mixture caused by throttle position inaccuracies.
  • Vehicle may enter 'limp mode', severely limiting speed and acceleration capabilities.

Possible Causes

Most common causes of P0120 (ordered by frequency):

  1. The most common cause is a faulty throttle position sensor, which occurs in about 70% of cases. This can stem from wear and tear, leading to inaccurate voltage readings.
  2. Corroded or damaged wiring in the TPS circuit is the second most common cause, as it can disrupt the signal sent to the ECU.
  3. A third cause could be a faulty Engine Control Unit (ECU). Regular software updates and checks can help prevent this issue.
  4. Less common but serious causes include vacuum leaks that can affect the throttle response and engine performance.
  5. A rare cause could be an aftermarket modification that interferes with the factory throttle control system.

P0120 Repair Costs

Cost Breakdown by Repair Type

Throttle Position Sensor Replacement

Replacing the faulty throttle position sensor with an OEM part.

  • Total: $150 - $250
  • Success rate: 90%
Wiring Repair

Repairing corroded or damaged wiring in the TPS circuit.

  • Total: $100 - $200
  • Success rate: 85%
Money-Saving Tips for P0120
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional P0120 Diagnosis Process

Follow these systematic steps to accurately diagnose P0120. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)

Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)

Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Component testing - Use a multimeter to test the throttle position sensor voltage and ground (20-30 minutes)

Step 3: Component testing - Use a multimeter to test the throttle position sensor voltage and ground (20-30 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: System function test - Verify proper operation of the TPS and clear codes to check for recurrence (10-15 minutes)

Step 4: System function test - Verify proper operation of the TPS and clear codes to check for recurrence (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success (15-20 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: Throttle Position Sensor Replacement in a 2011 Honda Accord

Vehicle: 2011 Honda Accord, 85,000 miles

Problem: Customer reported check engine light and poor acceleration.

Diagnosis: Performed an OBD2 scan using GeekOBD APP which confirmed P0120. Visual inspection revealed corroded wiring.

Solution: Replaced the throttle position sensor and repaired the wiring.

Cost: $220 (sensor $150, wiring repair $70)

Result: Customer reported improved acceleration and no check engine light.

Case Study 2: Wiring Repair on a 2014 Toyota Camry

Vehicle: 2014 Toyota Camry, 60,000 miles

Problem: Engine hesitating and check engine light on.

Diagnosis: OBD2 scan indicated P0120, and testing revealed damaged wiring.

Solution: Repaired the corroded wiring in the TPS circuit.

Cost: $180 (wiring repair $180)

Result: Hesitation resolved and vehicle performance restored.

Diagnose P0120

Use GeekOBD APP for professional diagnosis!

  • Real-time data monitoring
  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: P0120
System: Powertrain (Engine, Transmission, Emissions)
Severity: HIGH
Category: Engine Codes