NOTE: If fault code SPN 3242 diesel oxidation filter (DOC) inlet temperature FMI any is present, repair it first. The fault indicates that the high idle regeneration (HIR) was aborted due to the DOC inlet temperature not reaching the minimum of 518°F to initiate dosing during a HIR. The CEL and MIL lamps will remain on until the fault is resolved or a successful regeneration is completed.

POSSIBLE ISSUES:1. Intake Throttle Valve – perform intake throttle service routine to see if commanded position can be achieved.2. Exhaust leaks.3. Intake manifold leaks.4. Charge air cooler (CAC) leaks.5. Jake brake operation.6. DOC inlet temperature sensor- Compare diesel oxidation filter (DOC) inlet temperature to the DOC outlet temperature and the diesel particulate filter (DPF) outlet temperature sensors with the key on, engine off.

NOTE: If codes 3242-xx exist, fix those first.

PROBABLE CAUSES:1. Intake throttle valve failure.2. Exhaust leaks.3 Intake manifold leaks.4. Charge air cooler leaks.5. Jake brake operation (not turning on).6. DOC inlet temperature sensor.7. ECM failure.8. Jack brake rocker arm shaft not installed properly or failed.