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P1891 Buick Code - Throttle Position Sensor PWM Signal Low

Quick Answer

The P1891 Buick trouble code specifically refers to the Throttle Position Sensor PWM Signal being low. Common causes include Faulty Throttle Position Sensor, Wiring issues or poor electrical connections, ECM software issues. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1891 Buick indicates Throttle Position Sensor PWM Signal Low.
Common causes
Common causes include Faulty Throttle Position Sensor, Wiring issues or poor electrical connections, ECM software issues.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P1891 Buick Description

The P1891 Buick trouble code specifically refers to the Throttle Position Sensor PWM Signal being low. The Throttle Position Sensor (TPS) is a crucial component of the vehicle's electronic fuel injection system, responsible for monitoring the position of the throttle valve and sending this information to the engine control module (ECM). The PWM (Pulse Width Modulation) Signal is a type of digital signal that the TPS uses to communicate throttle position data to the ECM.

OBDII Code P1891 Buick - Throttle Position Sensor PWM Signal Low
P1891 Buick Code - Throttle Position Sensor PWM Signal Low

Common Causes of P1891 Buick

  1. Faulty Throttle Position Sensor
  2. Wiring issues or poor electrical connections
  3. ECM software issues
  4. Throttle body malfunction
  5. Engine control module (ECM) failure

Symptoms of P1891 Buick

  1. Rough idling or stalling
  2. Reduced engine performance
  3. Poor fuel efficiency
  4. Check Engine Light illuminated
  5. Acceleration hesitation

How to Fix P1891 Buick

  1. Begin by diagnosing the issue using a diagnostic scanner to confirm the P1891 code.
  2. Inspect the Throttle Position Sensor and its wiring for any visible damage or corrosion. Replace the sensor if necessary.
  3. Check the electrical connections to ensure they are secure and free of any corrosion. Repair or replace any damaged wiring.
  4. Clear the trouble code from the ECM and perform a throttle position relearn procedure.
  5. Test drive the vehicle to confirm that the issue has been resolved and the code does not return.

Cost to Fix P1891 Buick

The cost of repairing a P1891 Buick trouble code can vary depending on the specific cause of the issue. In general, the cost of replacing a Throttle Position Sensor can range from $50 to $200, while addressing wiring or electrical issues may cost between $100 to $300. Labor costs can add an additional $80 to $150 per hour, with most repairs taking between 1 to 2 hours to complete. Overall, the total repair cost for this issue could range from $150 to $500, but it is advisable to obtain a specific estimate from a qualified auto repair shop based on the vehicle's make and model.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1891 Buick Code

1. What does the OBDII code P1891 mean on a Buick?

P1891 indicates that the Throttle Position Sensor (TPS) is detecting a low Pulse Width Modulation (PWM) signal, which suggests an issue with the TPS circuit or its functionality.

2. What are the common symptoms of a P1891 code on a Buick?

Symptoms may include poor acceleration, reduced engine performance, erratic idling, or the illumination of the check engine light.

3. What causes the P1891 code on a Buick?

Common causes include a faulty throttle position sensor, damaged wiring or connectors in the TPS circuit, or issues with the engine control module (ECM).

4. Can I drive my Buick with a P1891 code?

While the car may still be drivable, it could experience reduced performance and unsafe driving conditions. It’s best to address the issue promptly.

5. How do I diagnose the P1891 code on a Buick?

Start by checking the TPS and its wiring for damage or corrosion. Use a multimeter to test the TPS voltage and inspect the ECM for potential faults.

6. What repairs can fix the P1891 code on a Buick?

Repairs may include replacing the throttle position sensor, repairing or replacing damaged wiring, or reprogramming or replacing the ECM.

7. How much does it cost to fix the P1891 code on a Buick?

Repair costs depend on the issue. Replacing a TPS typically costs $100–$300, while ECM repairs or replacements can cost $500–$1,200.

8. Can a dirty throttle body cause the P1891 code?

Yes, a dirty or clogged throttle body can interfere with the TPS readings and trigger the code. Cleaning it may help resolve the issue.

9. Is the P1891 code specific to Buick vehicles?

No, the P1891 code can appear on other vehicles with similar systems, but its exact meaning and diagnosis steps may vary by manufacturer.

10. Will resetting the check engine light fix the P1891 code?

Resetting the light will clear the code temporarily, but the underlying issue must be fixed to prevent the code from returning.

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