How to Fix P1128 Throttle Position Sensor In Range But Higher Than Expected

Introduction

If you’re experiencing the P1128 error code on your car, it means that the throttle position sensor is reading higher than expected. This can cause a variety of issues, including poor fuel economy, rough idling, and even stalling. Fortunately, fixing this problem is relatively simple and can be done at home with a few basic tools.

Step 1: Check the Throttle Position Sensor

The first step in fixing the P1128 error code is to check the throttle position sensor. This sensor is located on the throttle body and is responsible for telling the engine control module (ECM) how much air is entering the engine. To check the sensor, you’ll need a multimeter.

Start by disconnecting the electrical connector from the throttle position sensor. Then, set your multimeter to measure resistance and touch the probes to the two pins on the sensor. The resistance should be between 0.5 and 5 ohms. If the resistance is outside of this range, you’ll need to replace the sensor.

Step 2: Check the Wiring

If the throttle position sensor is reading within the correct range, the next step is to check the wiring. Start by inspecting the wiring for any visible damage or corrosion. If you notice any damage, you’ll need to repair or replace the wiring.

Next, use your multimeter to check the voltage at the throttle position sensor. With the key in the “on” position, touch the positive probe to the signal wire and the negative probe to a ground. The voltage should be between 0.5 and 1.5 volts. If the voltage is outside of this range, you’ll need to repair or replace the wiring.

Step 3: Check the Throttle Body

If the throttle position sensor and wiring are both in good condition, the next step is to check the throttle body. Start by removing the air intake hose from the throttle body. Then, use a flashlight to inspect the throttle body for any visible damage or debris.

If you notice any damage or debris, you’ll need to clean or replace the throttle body. To clean the throttle body, use a throttle body cleaner and a soft-bristled brush to remove any dirt or debris. Be sure to clean both the inside and outside of the throttle body.

Step 4: Reset the ECM

Once you’ve checked and repaired any issues with the throttle position sensor, wiring, and throttle body, the final step is to reset the ECM. This will clear the error code and allow the ECM to relearn the correct throttle position.

To reset the ECM, disconnect the negative battery cable for at least 10 minutes. Then, reconnect the cable and start the engine. Allow the engine to idle for a few minutes before driving.

Conclusion

Fixing the P1128 error code is relatively simple and can be done at home with a few basic tools. By checking the throttle position sensor, wiring, and throttle body, you can identify and repair any issues that may be causing the error code. Remember to reset the ECM after making any repairs to clear the error code and allow the ECM to relearn the correct throttle position.

FAQs

1. Can I drive my car with the P1128 error code?

While it’s possible to drive your car with the P1128 error code, it’s not recommended. This error code can cause a variety of issues, including poor fuel economy, rough idling, and even stalling. It’s best to fix the issue as soon as possible to avoid any further damage to your car.

2. How much does it cost to replace a throttle position sensor?

The cost of replacing a throttle position sensor can vary depending on the make and model of your car. On average, you can expect to pay between $50 and $200 for the part and labor.

3. How often should I clean my throttle body?

It’s recommended to clean your throttle body every 30,000 to 50,000 miles. This will help to ensure that your engine is running smoothly and efficiently.