Possible causes

– Faulty Manifold Absolute Pressure Sensor
– Manifold Absolute Pressure Sensor harness is open or shorted
– Manifold Absolute Pressure Sensor circuit poor electrical connection

Tech notes

There is a factory service bulletin for the following Honda models:

2001 Honda Odyssey
2003 Honda Odyssey
2003 Honda Pilot
Honda Factory Service Bulletin OBDII Code P1129

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Engine hard to start
– Rough or erratic idle speed

P1129 HONDA Description

The Manifold