Engine-Codes.com
Engine-Codes – Honda – P1128 1999 Honda Civic

P1128 1999 Honda Civic Code - Manifold Absolute Pressure Sensor Signal Lower Than Expected

Quick Answer

The P1128 code on a 1999 Honda Civic indicates that the Manifold Absolute Pressure (MAP) sensor is providing a signal that is lower than expected by the Engine Control Module (ECM). Common causes include Faulty MAP sensor, Vacuum leak in the intake system, Clogged or restricted intake manifold. 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
P1128 1999 Honda Civic indicates Manifold Absolute Pressure Sensor Signal Lower Than Expected.
Common causes
Common causes include Faulty MAP sensor, Vacuum leak in the intake system, Clogged or restricted intake manifold.
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 13, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P1128 1999 Honda Civic Description

The P1128 code on a 1999 Honda Civic indicates that the Manifold Absolute Pressure (MAP) sensor is providing a signal that is lower than expected by the Engine Control Module (ECM). The MAP sensor plays a crucial role in the engine's operation by measuring the pressure inside the intake manifold. This information is used by the ECM to calculate the air-fuel mixture and ignition timing for optimal engine performance. When the signal from the MAP sensor is lower than expected, it can lead to a variety of issues that affect the vehicle's performance.

OBDII Code P1128 1999 Honda Civic - Manifold Absolute Pressure Sensor Signal Lower Than Expected
P1128 1999 Honda Civic Code - Manifold Absolute Pressure Sensor Signal Lower Than Expected

Common Causes of P1128 1999 Honda Civic

  1. Faulty MAP sensor
  2. Vacuum leak in the intake system
  3. Clogged or restricted intake manifold
  4. Wiring/connectivity issues between the sensor and ECM
  5. ECM software or hardware issues

Symptoms of P1128 1999 Honda Civic

  1. Poor engine performance
  2. Reduced fuel efficiency
  3. Hesitation or stumbling during acceleration
  4. Rough idling
  5. Stalling

How to Fix P1128 1999 Honda Civic

  1. Begin by conducting a visual inspection of the MAP sensor, intake manifold, and vacuum lines for any signs of damage or wear.
  2. Use a scan tool to monitor the sensor's output voltage and compare it to the manufacturer's specifications.
  3. Test the sensor's operation by applying vacuum pressure to it and checking for a corresponding change in voltage output.
  4. If the sensor is faulty, replace it with a new one following the manufacturer's guidelines.
  5. Clear the diagnostic trouble codes from the ECM and perform a test drive to ensure the issue has been resolved.

Cost to Fix P1128 1999 Honda Civic

The cost of repairing a P1128 code on a 1999 Honda Civic can vary depending on the specific cause of the issue. Typically, the cost of a new MAP sensor ranges from $50 to $150, while labor costs for diagnosis and replacement can range from $100 to $300. Overall, the total repair cost could be between $150 and $450. It is important to note that these are rough estimates, and actual costs may vary based on factors such as location, vehicle make and model, and labor rates at the repair shop. It is recommended to obtain quotes from multiple shops to find the best price for the repair.

Need more information about the P1128 1999 Honda Civic code?

Need more information on how to fix the P1128 1999 Honda Civic code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1128 1999 Honda Civic code diagnosed by a professional: Find a repair shop in your area

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 P1128 1999 Honda Civic Code

1. What are common symptoms of OBDII code P1128 on a 1999 Honda Civic?

- Common symptoms include poor engine performance, rough idling, reduced fuel efficiency, and potentially stalling or hesitation during acceleration.

2. What causes the OBDII code P1128 on a 1999 Honda Civic?

- The code P1128 usually indicates a problem with the Manifold Absolute Pressure (MAP) sensor signal being lower than expected, which can be caused by a faulty MAP sensor, vacuum leaks, or issues with the intake system.

3. How can I diagnose the cause of OBDII code P1128 on my 1999 Honda Civic?

- To diagnose the issue, you can start by checking the MAP sensor for proper operation, inspecting for any vacuum leaks in the intake system, and ensuring the intake manifold is tightly sealed.

4. Is it safe to continue driving my 1999 Honda Civic with OBDII code P1128?

- It is not recommended to continue driving with the code P1128 present, as it can lead to further damage to the engine and potentially worsen the symptoms over time.

5. Can I repair OBDII code P1128 on my 1999 Honda Civic myself?

- Depending on your level of automotive knowledge, you may be able to repair the issue yourself by replacing the faulty MAP sensor, fixing any vacuum leaks, or addressing intake system problems. However, professional assistance may be needed for accurate diagnosis and repair.

6. Will resetting the OBDII code P1128 on my 1999 Honda Civic make it go away permanently?

- Simply resetting the code may temporarily clear the warning light, but if the underlying issue causing the code is not addressed, it is likely to reappear once the problem persists.

7. How much does it typically cost to repair OBDII code P1128 on a 1999 Honda Civic at a mechanic?

- The cost of repairing the P1128 code can vary depending on the exact cause of the issue, but it may involve replacing the MAP sensor, fixing vacuum leaks, or other related repairs. Costs can range from $100 to $300 or more.

8. Can a dirty air filter trigger OBDII code P1128 on a 1999 Honda Civic?

- While a dirty air filter may impact engine performance, it is not a common direct cause of the P1128 code. However, ensuring regular air filter maintenance is still important for overall engine health.

9. Will driving in extreme weather conditions affect OBDII code P1128 on a 1999 Honda Civic?

- Extreme weather conditions can potentially exacerbate existing issues related to the MAP sensor or intake system, leading to the triggering of the P1128 code. It is advisable to address any underlying problems regardless of weather conditions.

10. How does the OBDII code P1128 on a 1999 Honda Civic impact emissions and environmental concerns?

- The P1128 code typically indicates a problem affecting the fuel-air mixture, which can lead to increased emissions and environmental pollution. Resolving the issue promptly can help reduce the vehicle's negative impact on the environment.

Discuss the causes and fixes for P1128 1999 Honda Civic OBDII Code

Submit a New Comment

Code P1128 1999 Honda Civic comments

No comments found for this page.