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Pete
Pete, Technician
Category: Australia Car
Satisfied Customers: 24697
Experience:  Over 17 years diagnosing and repairing various model vehicles with some certifications and training.
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Mercedes

Customer Question

Mercedes
Submitted: 10 months ago.
Category: Australia Car
Expert:  Pete replied 10 months ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

The first thing to inspect here is to check all oxygen sensors wiring and wiring connections for any corrosion,shorting or damage at all.If a fault is found with any of the wiring or wiring connections it will need repaired to correct this fault here.I have seen oxygen sensor wiring connection and wiring faults on a different oxygen sensor other then what the codes are setting for cause the issue for these codes setting and had to repair the wiring.If all wiring and connections are checked/traced and inspected and found o.k. let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 10 months ago.
Hi Pete, I have checked all the connections by the O2 sensor is no corrosion or broken wire detected by the plug, all the wiring goes inside car underneath the floor carpet, before I start pulling out carpets and remove seats, I would like to check what are correct readings at each pin by the plug and maybe check connection at the ECU, but I need the information to be able to, Like I said the O2 sensor is new I also swapped Left to Right, The fault remain the same at Bank2 Sensor1 fault code P0150 and P0155. If you can provide me with a step by step repair produre
Thanks Andrei
Expert:  Pete replied 10 months ago.

O.k.,the code is for o2 sensor bank 2 sensor 1 operation and o2 sensor bank 2 sensor 1 heater control operation.This would be the drivers side oxygen sensor before the catalytic converter.

You should have a ground on the brown wire which leads directly to the engine computer

The white wire with blue stripe should have a varying voltage usually starting at higher (around 12 volts) when the engine is first started cold in the morning and may decrease voltage as the sensor heats up.This signal also comes directly from the engine computer.

The red wire with green stripe is also the heater control circuit which loops to the passenger side front oxygen sensor.

The yellow wire is the signal wire that feeds the millivolt signal back to the computer.This signal will vary around 100 MV to 1000MV back and forth as the engine is running.

Check and see which signals you have here.If you have the MV signal at the sensor then this indicates a wiring fault to the engine computer or the engine computer itself is at fault.You want to connect your multi meter to ground on DC volts setting to test this MV signal.

Thanks Pete

Customer: replied 10 months ago.
Hi Pete,
I have done the following testes, Step 1.Engine started O2 sensor at first start cold, Brown wire 13V, Step 2. The white wire with blue stripe varying voltage 12-13 Volts, but soon as engine staring to worm up volts drops to 0.60 Volts and stayed there. Step 3. The red wire with green stripe has 13.86 volts engine cold the raise to 14volts engine worm. Step 4. The yellow wire test, if I set multi-mater at MV I had no reading if I changed to Volts reading was vary around 0.85 volts to 1.5 volts same reading engine cold and engine worm. The test has been completed with O2 sensor plugged in then used back-testing pin to check voltage. I also unplugged ECU the check for any corrosion contamination or broken wire , I have not detected any issues visually. I suspect next step would be continuity test on each wire from O2 sensor plug and ECU connector plug, then ECU test Could you please Gide me to next step regarding test results.
Thanks, Andrei
Expert:  Pete replied 10 months ago.

O.k.,it sounds like you have the correct voltages at the sensor.Test these signals at the ecm and see if the signals are all the same.If they are then test the resistance of each wire from the ecm to the sensor connector with both the ecm and sensor unplugged.You should have around 0 ohms resistance.Then test each wire for a resistance to ground with these unplugged.You should have an open circuit reading.If these are all o.k. and with the sensor signals looking to be o.k. here this sounds like the ECM itself is at fault needing replaced.

Let me know if you need anything else and feel free to rate my help here.

Thanks Pete

Customer: replied 10 months ago.
Hi Pete,
Can you give me the exact wiring diagram to the driver side O2 sensor which showing the wiring location in the ECM plug?
Thanks Andrei
Customer: replied 10 months ago.
Hi Pete, Is any way to have this pictures in better resolution, I hardly can read them.
Expert:  Pete replied 10 months ago.

I was looking at them the same way hard to read for me as well.I tried to blow them up but it just made them really blurry.Unfortunately this is the only diagram connection issue I show for this here.I wish I had more on this.

Thanks Pete

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