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I started getting this code last summer and just reset the CEL about every 6 weeks. I started driving the car again in April and the code started reappearing more frequently.
According to the DME 7.2 Codes this was a Bank 2 Sensor 2 O2 Sensor that needed to be replaced. I put in a new Bosch OEM type sensor and the code returns every 3 restarts after I reset it.
I checked the connections and everything looks good. I am reading and resetting the code with my Torque App through a Bluetooth OBDII adapter. Any chance it could be giving me the wrong code?
Any chance I have my "Banks" swapped. I thought Bank 2 was the passenger side and the sensor 2 is actually over on the drive side.
Any thoughts or help would be greatly appreciated!
The car is a '01 C2 which should be using DME 7.2 codes.
The Bosch part number is 15250. I should add that I have always received good real-time voltage readings from the sensor when I display them on my torque app. Or at least the sensor was transmitting voltage that was similar to the other O2 sensor most of the time. I think this would point to a heater issue rather than a wiring issue.
The car is a '01 C2 which should be using DME 7.2 codes.
The Bosch part number is 15250. I should add that I have always received good real-time voltage readings from the sensor when I display them on my torque app. Or at least the sensor was transmitting voltage that was similar to the other O2 sensor most of the time. I think this would point to a heater issue rather than a wiring issue.
Great. Yes, Bosch 15250 is the correct post-cat sensor for your model. It's not surprising the sensor is working correctly as far as its signal is concerned because the code P1118 is actually complaining about the heater circuit on that sensor which are pins 1 and 2 of the sensor. Most likely you have a wiring issue.
Pin 1 (Black wire) gets +12v when key ON engine OFF.
Pin 2 (Black/Red wire) is connected to the DME plug II/pin 1.
You can check the following:
- unplug the sensor. Check the heater resistance by measuring resistance between pin 1 and pin 2 on the sensor. It should be ~2.6 ohm
- Key ON engine OFF, check the car harness side pin 1 should have +12v
- Disconnect the DME side plug II and check continuity between plug II/pin 1 and O2 sensor socket side pin 2. They should connect.
Any chance I have my "Banks" swapped. I thought Bank 2 was the passenger side and the sensor 2 is actually over on the drive side.
Torque Pro and the codes are correct and so is the bank 2 postcat sensor location. Your postcat sensor is quite far from the cat, right? The MkII postcat sensor is right in the middle of the cat.
Thanks to all for the help so far but I am stuck again.
The wiring diagram shows that the O2 sensor pin 2 connects to pin 1 on the DME plug. Where does the O2 sensor pin 1 connect on the DME plug?
If I disconnect the sensor, I can get continuity between the DME plug II pin 1 and the car harness pin 1 but not the car harness pin 2. This seems to indicate that I either have a problem or the wrong wiring diagram.
The O2 sensor pin 1 connects to 12v supplied by a relay, which activates whenever your key is at the last position before crank.
That pin 1 on the sensor should not concern you anyway as you already verified you got 11.9v on that pin before?
The DME grounds pin 2 of the sensor to power its heater, pwm I think.
Originally Posted by ttreat
Thanks to all for the help so far but I am stuck again.
The wiring diagram shows that the O2 sensor pin 2 connects to pin 1 on the DME plug. Where does the O2 sensor pin 1 connect on the DME plug? Does it connect to ground?
If I disconnect the sensor, I can get continuity between the DME plug II pin 1 and the car harness pin 1 but not the car harness pin 2. This seems to indicate that I either have a problem or the wrong wiring diagram.
I missed this part of your post. My diagram shows exactly the same so I think the diagram is correct. Also, it's easy to remember for O2 sensors, all solid black wires are +12v. You can see that pin 1 of O2 sensor harness side is black and pin 2 is black/red.
Your measurement is indeed strange if true. Can you check if the DME plug II pin 1 cable is black/red and it matches the wire color on the pin 2 of the O2 sensor? Even if that wire is shorted to pin 1 of the O2 sensor, you should still have continuity between the DME and the pin 2 of the O2 sensor.
Any more history of the car on how it got this error msg? Someone messed with the wiring before?
Fascinating and good work Ahsai! Very good idea to check the black/red wire trace from the sensor plug to the DME. Sounds like something is miswired. I think you are spot on.
Hey Joe, I duuno as there are many questions still. If it's truly the same wire but with no continuity, that means the wire was cut and then shorted to the other wire/pin...quite unlikely. This one is intriguing for sure so far
Originally Posted by DBJoe996
Fascinating and good work Ahsai! Very good idea to check the black/red wire trace from the sensor plug to the DME. Sounds like something is miswired. I think you are spot on.
I finally got a little time to look into the problem a little further and found that I deserve a really good dope slap! The initial fix was done in a hurry with 10 minutes of spare time. Obviously this led me to spend unnecessary additional time trouble shooting. After questioning a number of things that didn't make sense, including non matching wire colors to the schematic, I thought I should double check the other sensor locations and wire colors and quickly realized that I replaced the wrong sensor. So far the CIL has not returned.
06-29-2016, 01:28 PM
P1118 Engine Code Won't Go Away
