Diesel Engine Extended Idling And DTCs P0401 P244B P244C - keywords 6.6 clean cool cooler DPF EGR exhaust filter idle indicator IPC message particulate regen regeneration service

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

A dealer may encounter a customer concern of DTC P0401, P244B, P244C, or a DPF (Diesel Particulate Filter) clean filter message.

Engineering is investigating this concern when it occurs on 2007-2008 6.6L (RPO code LMM) Diesel engine equipped vehicles.

This PI is directed to vehicles used in a very specific drive cycle. Vehicles used for shuttle buses and/or ambulances (and other similar applications) may be seeing extended idle times and short drives. The extended idle and short drives may induce EGR and DPF concerns.

Complete the current diagnostics for any DTC or symptom found. If a dealer has encountered DTC P0401, P244B, P244C or a DPF clean filter message due to the vehicle drive cycles (as described above) continue with the information found in this PI.

1. Make sure the customer/driver has been given a copy of the "Diesel Particulate Filter Operation" (located in diesel engine owners manual supplement), and the SI document titled,"Diesel Particulate Filter System Description." Many times there are multiple drivers of these vehicles and they have not received these important operating descriptions.
2. Extended idle time may induce DTC P0401 to set. If a vehicle has been idling for extended periods of time, the exhaust gases may have restricted the EGR cooler. If an EGR cooler has become restricted the only repair (at this time) is to replace the EGR cooler. At idle with the engine at operating temperature the EGR valve is normally open. If the high idle switch is utilized the RPM will raise and the EGR valve will close. No gases will flow through the EGR system and EGR cooling clogging will be less likely to occur. If a customer is going to idle the vehicle for more then 10 minutes at a time, using the high idle switch (If equipped) is highly recommended (refer to owners manual for 2008 high idle control).
3. If a vehicle has been used for idling with short drive cycles, the DPF may not reach a calibrated temperature inducing a P244C to set. If a dealer has encountered a repeat P244C, and the customer drives the vehicle as described, advise the customer to use tow haul mode when driving. The use of tow haul mode will keep engine temperature up (at lower speeds) and facilitate a complete DPF cleaning.
4. Leaks at the turbo to exhaust pipe connection may also cool DPF operation. Use the SI document for Charge Air Cooler Diagnosis (Full System Air Leak Test) to verify the turbo to exhaust down pipe connection is not leaking and repair as necessary.
5. In some cases the driver has noticed a "clean filter message" and continued to idle the vehicle. As per the owner's manual description, the vehicle must be driven above 30 mph (50 km/h) until the warning message goes off. This will take about 20 minutes. If the vehicle is not driven, a P244B may be induced.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.