Renewed Oxygen Sensor - Defective?
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Joined: Sep 2014
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E320 CDI
Renewed Oxygen Sensor - Defective?
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 other than "Check Engine" light, no fault noted in engine performance. Vehicle has received timely maintenance, adhering 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 accordingly (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? Intake system vacuum leak? Wiring defect?
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 other than "Check Engine" light, no fault noted in engine performance. Vehicle has received timely maintenance, adhering 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 accordingly (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? Intake system vacuum leak? Wiring defect?
Out Of Control!!
Joined: Apr 2019
Posts: 11,930
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Code came back...
you changed the upstream O2/Lambda, cleared the code then it came right back....
Can you compare both bank Fuel Trims... they should be closely similar but in your case Bank2 will be stuck lean.
Now that your sensor is good, we know something else is wrong, right?
The bank2 sensor harness may be faulty, shorted to GND, bad fuse, bad ECU control unlikely but possible... short term fuel trim will show obvious discrepancy from erroneous input.
Your Bank1 deserves a fresh sensor of the same age. This will help your engine V-banks stay balanced. Mixing new/old sensor is source of vibrations.
Running fresh upstream sensor is a very positive maintenance item.
Can you compare both bank Fuel Trims... they should be closely similar but in your case Bank2 will be stuck lean.
Now that your sensor is good, we know something else is wrong, right?
The bank2 sensor harness may be faulty, shorted to GND, bad fuse, bad ECU control unlikely but possible... short term fuel trim will show obvious discrepancy from erroneous input.
Your Bank1 deserves a fresh sensor of the same age. This will help your engine V-banks stay balanced. Mixing new/old sensor is source of vibrations.
Running fresh upstream sensor is a very positive maintenance item.
Last edited by CaliBenzDriver; Jan 28, 2022 at 03:30 AM.
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Joined: Oct 2020
Posts: 1,184
Likes: 891
From: Arizona
Bentley Continental GT; AMG GT
you changed the upstream O2/Lambda, cleared the code then it came right back....
Can you compare both bank Fuel Trims... they should be closely similar but in your case Bank2 will be stuck lean.
Now that your sensor is good, we know something else is wrong, right?
The bank2 sensor harness may be faulty, shorted to GND, bad fuse, bad ECU control unlikely but possible... short term fuel trim will show obvious discrepancy from erroneous input.
Your Bank1 deserves a fresh sensor of the same age. This will help your engine V-banks stay balanced. Mixing new/old sensor is source of vibrations.
Running fresh upstream sensor is a very positive maintenance item.
Can you compare both bank Fuel Trims... they should be closely similar but in your case Bank2 will be stuck lean.
Now that your sensor is good, we know something else is wrong, right?
The bank2 sensor harness may be faulty, shorted to GND, bad fuse, bad ECU control unlikely but possible... short term fuel trim will show obvious discrepancy from erroneous input.
Your Bank1 deserves a fresh sensor of the same age. This will help your engine V-banks stay balanced. Mixing new/old sensor is source of vibrations.
Running fresh upstream sensor is a very positive maintenance item.
