Excessive nitrogen oxides (NOx) emission
Perform troubleshooting referring to the followings when ECM has detected no DTC and no abnormality has been found in Visual Inspection:M13A with VVT and Engine Basic Inspection:M13A with VVT .
Condition Possible Cause Action
Excessive nitrogen oxides (NOx) emission
Improper ignition timing
Lead contamination of catalytic converter
Check for absence of filler neck restrictor
Faulty EGR system
Fuel pressure out of specification
Closed loop system (A/F feed back compensation) fails
– Faulty TP sensor
– Poor performance of ECT sensor or MAF sensor
Faulty injector(s)
Faulty ECM
Camshaft position control (VVT) system out of order