Here are a list of possible causes.
Malfunctioning or improperly adjusted EGR valve
Failed oxygen sensor
Leak in exhaust tubing upstream of converter
Excessive carbon deposits in combustion chamber
Improper spark advance
Blocked coolant passage
Overly lean air-fuel mixture
Damaged cold air duct
Failed or malfunctioning catalytic converter
Corroded or damaged engine sensor electrical connections
EGR valve is at rear of engine but 'I could not find any diagrams to indicate the location.
Friday, October 1st, 2010 AT 9:18 AM