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Discussion Starter #1 (Edited)
So I got a Service Engine Soon light tonight and pulled the codes with my Peake reader.

1b DM-TL switching valve
8f E-box fan
26 “PreCat oxygen sensor heater control, Cyl #5-8”

Is the 1b a code or is it a reference to look in the table?

Are these other parts essential to change at this moment?

Thanks
 

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The 1b at the beginning is actually the reference as to what table to look under.

The Ebox fan code isn't something personally I would say needed changing imminently given its winter time now and temps have dropped but do it sooner rather than later.

Your O2 fault I would look at when I could, surely in the sticky at the top someone has posted about such an issue?
 

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So I got a Service Engine Soon light tonight and pulled the codes with my Peake reader.

1b DM-TL switching valve
8f E-box fan
26 “PreCat oxygen sensor heater control, Cyl #5-8”

Is the 1b a code or is it a reference to look in the table?

Are these other parts essential to change at this moment?

Thanks
The pre-cat O2 sensor heater fault is what is bringing in the SES light. A new sensor will most likely fix it, but if you can handle a DMM, there is a simple check you could do to confirm this.
Disconnect the electrical connector near the sensor (under the car but easy to get to)
Measure the resistance across pins 1 and 2 on the sensor connector (pin numbers are on the connector, these are the white wires).
Resistance with sensor at room temp should be 2.5 ohms. If 0 ohms or "OL", the heater has failed.
If the resistance is OK, there are some other checks you can do but they are trickier.
 

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I just got the Code 28 “After Cat oxygen sensor heater control, Cyl #5-8” I assume the troubleshooting is the same? Is the sensor easy to find? Thanks!
 

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Yes, same check applies. The connectors are in a little black box on each side under the car. This pic shows the box on the bank 1 side. I suggest taking a pic when you get the cover off to show the wiring layout for putting it back together.

DSC00055.JPG
 

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It looks like a couple of nuts need to be loosened that hold the box on that covers the connectors. Anything vulnerable there? Do the connectors come apart easily? Maybe more important, do they go back together easily? :3: Good idea to take a photo first!
 

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They're plastic nuts IIRC, so go easy on them. If the protruding stud is very rusty, cleaning the exposed threads up with a small wire wheel on a Dremel will help.

Like any electrical connector that's been on for a while, they can be a bit stubborn coming off. Look at them closely and you will see the two tabs on one half that locate and lock over two dimples on the other half. You need to gently pry up the tabs while pulling apart. (If the tabs are on the sensor side connector, you don't need to be so gentle.)

They click back together pretty easily but may require a firm push to get the tabs locked.
 

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Thank you so much for the info; a big help! I feel better about tackling it. I hope to remember to share some feedback for future generations. ;-)
 

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Well, NOW I know why the sensor isn't working! I'll have to get her up so I can see if I am so lucky that it just came unplugged. Must have run over something that hooked the cable.
 

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It's strange that you have codes for the heaters and don't have codes for no signal from that O2 sensor, either 0C for pre-cat or 58 for post cat.

If the connectors have been pulled apart on both sensors, you might want to pull the cover off the bank 1 side connectors to see how the wiring runs, as there have been a few threads on here about people messing up the connections after replacing both sensors as it is possible to connect the post cat sensor right to the pre-cat sensor. This brings in the heater codes.
 

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The connectors for the after-cat sensor had come apart but the pre-cat sensor connectors were still made up and snug in the cover. However, the plastic cover is broken at the rear mounting tab. Managed to re-connect the cable for the after-cat sensor and snap the connectors into the cover without removing it. It isn't ideal - I need to replace the cover or otherwise secure it better - but it's pretty stable. Reset the codes, fired her up, and no Service Engine Soon light - yay! Thanks for your help, 68FB!
 

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This is not strange. If you plug in, incorrectly you get only the heater code. Why would you expect more if the sensor was simply disconnected?
 

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I figured if the signal from a a critical sensor like that was lost, the DME would be smart enough to set a code. IIRC, I got 0C and 0D when I disconnected the precats a couple of years ago. The INPA message with those is "short circuit to ground or value too small".
 

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I would say that is more odd. I had a broken wire to the O2 on the driverside, pre, for I don't know how long. I only get a not ready on OBDII and have no codes stored in the DME. Brought to my attention at the Etest. I am guessing it happened when I broke my bumper a year and so ago. NFLD roads yeka freka **** nice to be back in Ont.
 

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I did a quick search on the 0C and 0d codes and found a few threads but they all just petered out and none conclusively said what happened and how it was fixed.

I'll have to do the disconnect again when she's back in the spring. Maybe I'm getting my tests mixed up.
 
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