P1128 – Honda DTC

Honda DTC P1128 – MAP Lower Than Expected

DTC P1128 meaning on Honda

1. DTC P1128 indicates that the Manifold Absolute Pressure (MAP) sensor is reporting a lower than expected reading to the Engine Control Module (ECM) on a Honda vehicle.

Honda DTC P1128 symptoms

• Check Engine Light (CEL) illuminated on the dashboard.
• Reduced engine performance or power.
• Possible rough idling or stalling.

Honda DTC P1128 causes

• Defective or failing MAP sensor.
• Vacuum leaks in the intake system.
• Issues with the wiring or connectors related to the MAP sensor.

Honda DTC P1128 seriousness

1. If left unresolved, DTC P1128 can lead to poor engine performance, reduced fuel efficiency, and potential damage to other engine components.

How to diagnose DTC P1128 on Honda

1. Use a diagnostic scanner to retrieve the specific trouble code and related freeze frame data.
2. Inspect the MAP sensor and its wiring for any visible damage or corrosion.
3. Check for vacuum leaks in the intake system using a smoke machine or propane torch method.

How to fix DTC P1128 on Honda

1. Replace the faulty MAP sensor if it is determined to be the cause of the issue.
2. Repair any vacuum leaks in the intake system and ensure all connections are secure.
3. Clean or replace any damaged wiring or connectors related to the MAP sensor.

How to erase DTC P1128 on Honda

1. After addressing the root cause of the issue, use a diagnostic scanner to clear the trouble code from the ECM’s memory.
2. Ensure that the CEL is no longer illuminated and perform a test drive to verify that the issue has been resolved.