E53 4.6is Trouble Codes 1A, 1B, 16, 17 (generic P1176)

[JohnI.X5]

Vehicle:

• 2003 BMW E53, 4.6 is, (M62 TU)
• 120,000 miles (bought nearly new July 2003 with 5,000 miles)
• St Petersburg, Florida (No rust anywhere)

Trouble Codes:

• Generic DTC code reported: P1176
• Used Foxwell 710 Scanner with BMW features to determine BMW unique codes:

• 16 DME: Oxygen-sensor ageing before cat. conv., bank 2 (TV)
• 1A DME: Multiplicat. mixture adaptation, bank 1, control limit reached
• 1B DME: Multiplicat. mixture adaptation, bank 2, control limit reached

Analysis:

• Was experiencing DTC “16” (and one time “17” ) for some time, 6 months, 4,000 miles. After resetting it would always return. Swapped L and R pre-cat oxygen sensors. No change in behavior.
• Then started receiving “1A” and “1B” regularly—sometimes in as little as 3 miles of driving. Always "1A" first then "1B" later, I believe.
• Engine running poorly.

Diagnosis:

• Research for these codes told of people who replaced sensors, cats(!) and still had the problem. No way all those parts could have failed at the same time to produce those codes.
• Practiced advice of YouTube heroes Eric (Main Street Auto) and Ivan (Pine Hollow Auto Diagnostics) to think about the problem before firing the parts cannon. Based on the fact that errors were reported on both left and right sides of the engine, what was shared between them? Intake manifold, MAF are about it. No DTC for MAF but computer might not know the MAF is reporting bogus numbers and I don’t have a sophisticated scanner to perform proper diagnosis.
• Nonetheless, I had a new MAF that I had used temporarily earlier after having problems with ABS and poor performance (ABS fixed now.) so I could swap out the suspect MAF. (The suspect MAF was the original MAF with about 110,000 miles.)
• Success! “New” MAF seems to have cleared performance issues and X5 is running smoothly for the first time in a while.

Conclusion:

• Mixture Adaptation Control Limit Reached (Codes “1A” and “1B”) appears to be triggered by the MAF. Replace it!
• Have fingers crossed that codes "16" (and "17") are cured as well, but they take longer to set if still present. {I'll update if needed.)