Excessive White Or Blue Smoke From The Exhaust - keywords 6.6 compression cool coolant cooler cylinder diesel DPF engine exhaust gray leak LMM loss md sensor tail tailpipe turbo

This PI was superseded to update Recommendation/Instructions. Please discard PIP4137.

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 excessive white, blue, or gray smoke from the tailpipe of a 2007 6.6 (RPO code LMM) diesel engine.

The excessive smoke will usually be noticed during a Diesel Particulate Filter (DPF) Regeneration. There may also be a strong sulfur odor from the exhaust when the DPF regeneration occurs.

The excessive smoke may be caused by the use of high sulfur fuels. The 6.6L LMM diesel engine is designed to operate on Ultra Low Sulfur Fuel (15 PPM).

Fuels tested that caused this type of smoking have been 500 PPM or greater (as high as 1500 PPM).

If the excessive smoke is occurring during DPF regeneration, discuss and verify proper fuel use with the customer. All diesel fuel pumps must be clearly labeled with the current sulfur content of the fuel (see bulletin number 06-06-04-041). Off road, marine, and locomotive fuels (black pump label) may have higher then 500 PPM sulfur. Off road fuels were not regulated to 500 PPM (or less) until June of 2007.

Evaluate smoking concerns after the vehicle has been running on a fresh tank of Ultra Low Sulfur Fuel.

Dealers are to complete a service regeneration when known good fuel is in the fuel tank.

Advise customers that Ultra Low Sulfur Fuel (15 PPM) is required for all 2007 6.6L Duramax Diesel Engines (with RPO code LMM).

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.