I’m getting CEL codes all relating to passenger downstream sensor.

My air filter was very dirty, and I hoped that was it. No dice.

The sensor is clean, not covered in oil. (Never thought to look further up the cable tho, I do have valve cover leak that could possibly be getting on something that side).

Ive had the truck (04) 10 years, never had O2 issues previous.

What to check before I look at swapping sensors out? Would I swap 2 at a time? Bosch to swap in right, for less chance of trouble?

Thanks.

 

Swap left and right first, see if it follows the sensor.

 

Remember too that the downstream O2 sensors have nothing to do with fuel delivery or anything else about how the engine runs. Their sole purpose is to monitor efficacy of the catalytic converters

In other words, go ahead and address the issue, but I wouldn't consider it urgent.

 

Thanks guys.

Managed to get both plugs off. Pass side was awkward. Swapping them is great idea to check. So obvious, I didn’t think of it.

Ordered a sensor socket, no way they are coming out with a regular wrench.

Sat soaking in PB now. They will get ‘the bar’ tomorrow.

I suppose it isn’t urgent, you’re right. But I really don’t like the CEL on.

The Bosch replacements are $35. Figured they’d be much more expensive than that.

 

One side came free, the other absolutely didn't. Started to round. Stopped trying.

I’ve managed to loosen the suspicious one, so have ordered a sensor to try my luck.

1. am I ok just swapping one?

2. there seem to be different ones. I don’t see a guide for which is which. Ordered the one below. Any chance that’s right? Bank 2 sensor 2.

https://a.co/d/cIleoOw

 

You didn't specify, but I'll presume the sensor that came out is B2P2.

Replacing just one is fine. Long-ago, a once-prominent forum member always advocated replacing O2 sensors in pairs. That made no sense to me. Although in 22 years I have not (yet) needed to replace a downstream sensor, I have replaced more than my share of upstream O2s, always one at a time with no problems.

FWIW, a few months ago I was trying to help a local owner replace the upstream sensors in his DII. We tried everything we could. We had multiple extensions on the O2 socket to put the breaker bar at a height where we could add a cheater pipe. Nuthin'. He ended up taking it to a muffler shop, and getting them out was very difficult for them too.

 

You are definitely OK just replacing one for the downstream sensors, but I still think it’s a good idea to replace the upstream ones in pairs because they’re the ones actually sending fueling data back to the engine. It’s conceivable that if you only replace one you risk running one bank of your engine differently than the other. Now, I grant you it probably wouldn’t be too bad as it would just send another code or run in open loop if it was really bad but it seems like a silly thing to risk.

 

Finally got done with this problem.

I couldn't chase the threads in the old O2 hole.

In the end I bought a weld on collar and plug. Welded the collar so its horizontal, and plugged the old hole.

Better news is the code is staying away, so that looks like my issue.

Next time, I'm just snipping the old O2 wire and welding a collar on straight away. Waste of effort trying to get those things out cleanly.

Thanks for the pointers.

 

Did you drop the Y pipe to do this? I made two extension cables and now that it’s stopped raining here I plan to swap the connections instead of the sensors to ensure the problem moves with the sensor first, then will replace the bad one. If I end up dropping the pipe I'll replace both for sure. Welding in a new bung has some appeal, sure would make the job simpler next time.

 

Maybe different for D2 vs D1, but each bank fuel trims are controlled separately on D1s. So if you just swap connectors, one side will force the other rich, and the other side will force lean and stick there with no modulation of fueling or O2 voltages. Bottom line is sensors need to be swapped to test, not only the wires.