O2 sensor confustion Topic is solved

mn11569 · Post by **mn11569** » 14 Nov 2005, 09:25

My 'Check Engine' light came on and the message display read 'emission service required.' I used an OBDII reader which revealed code P0050 which needed to be converted to the Volvo diagnostic code and I found 2 references both giving code ECM-210 Signal missing permanent fault however two different definitions were given:

1. Rear Heated O2 sensor (HO2S) Preheating, Bank 2

2. Front Lambda Probe Pre-Heating Bank 2

So my questions are:

1. Which one is correct or are they saying the same thing in two different ways?
2. How do I identify the exact O2 sensor that need to be changed?
3. Which side of the car is Band 2? (I can see two O2 sensors looking between the motor and the firewall)
4. Has anyone changed the O2 sensors in these cars that can share some input on tricks/issues that may cause problems?

Thanks,

Chapstick · Post by **Chapstick** » 15 Nov 2005, 13:02

Before you begin climbing under the chassis, open the underhood fuse box and check fuse #4 (assuming for your car, of course (check the lid cover for oxygen sensor fuse and check that number)(yellow, 20-amp). If it's good then we can start looking further. Is that the only P-code that you pulled?

mn11569 · Post by **mn11569** » 16 Nov 2005, 10:43

First of all thanks for responding.

Please note that I made a mistake on the ECM code. It should be ECM-2910.

Yes, the only P code was P0050.

I will check the fuse when I go home today since I am not driving it due to this problem

Thanks,
Mike

mn11569 · Post by **mn11569** » 18 Nov 2005, 06:31

Checked the fuse and it is not open.

Chapstick · Post by **Chapstick** » 20 Nov 2005, 20:42

This DTC is for the front heated oxygen sensor on bank 2. Bank 2 is for cylinders 4, 5, and 6. So, from underneath the car it is the sensor closest to the transmission. You could swap it with the front O2 on bank 1 to verify that it's not the wiring to the sensor. If it's give the same error code after swapping, then there are some checks you must do with a volt-ohm meter to check the wiring to the ECU.

Guest · Post by **Guest** » 21 Nov 2005, 10:26

OK, I will swap out the O2 sensors. Any special trick with these that I sould know about? Is it possible to just disconnect each sensor and switch the wiring?

Chapstick · Post by **Chapstick** » 22 Nov 2005, 13:09

You don't want to do that!! The ECM has control for each fuel injector and will increase or decrease pulse width to accommodate fuel conditions (rich or lean). Also, the front and rear sensors are paired with one another in diagnosing catalytic efficiency. I would suggest, depending on your flexibility, that you not drop the exhaust system completely. I'm only suggesting this if you feel comfortable giving it a shot. Exercise all the precautions (floor stands, exhaust is cool, etc.) and just disconnect the post converter connection to the exhaust pipe (two 12 or 13mm nuts, I believe). Slide under a well supported car from the front of the car. There is enough egress to stretch your arm over the cats to remove both front sensors. You won't be able to use a socket, though. Using an open end wrench (22mm) or an adjustable wrench, crack loose the fittings. It will be much easier if you disconnect the plug connectors first. This will help facilitate the sensor removals. Label which one came from which exhaust so you know what is being checked and when. Hope that helps. Let us know what you determine.

Guest · Post by **Guest** » 30 Nov 2005, 06:44

Looks like the connector became loose. I remember when the car was still under warranty the dealer thought the sensor needed to be changed however when I picked up the car they said they didn't need to change it out. They must have lost the little clips that hold the fitting together and used a tie wrap to hold it tight. I cleaned the connections and cleared the error. Seems to be working for now.......