2015 ML 350, M 276.9, 80K miles...


Fault code scan performed following illumination of "Check Engine" light.
Scan revealed the following codes and live data:

P227200 - signal of O2 sensor (cylinder bank 2) is shifted toward lean

P015700 O2 - sensor (cylinder bank 2) has a short circuit to ground

Voltage of O2 sensor downstream - pegged (static) at 0.010 V (normal range 0.100 - 0.820 V)

Vehicle is asymptomatic, otherwise; no fault noted in engine performance. Vehicle has received timely maintenance, according to Mercedes service schedule.



Renewed sensor with new Mercedes sensor, part # 008 542 39 18.

Cleared fault codes, drove vehicle 30 miles and rescanned:

"Check Engine" light persists, previous two existing fault codes are still present BUT... the voltage of the downstream sensor is now within range and fluctuates (no longer pegged at 0.010 V).

Any suggestions as to why the Motor Electronics system still reports these two fault codes? Is the new O2 sensor defective? Vacuum leak?

is there any oil in the harness?

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Try to do a smoke test on intake.

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Jim