Oxygen Sensor Replacement (Post #587) 9/16/2019


I’ve had some issues with the idling on the Big White Bus. Once she is warmed up when I come to a stop sign the idle drops to something like 300 rpms. And eventually she drops lower and finally dies.

I read online that the O2 sensors could be the culprit. I couldn’t remember the last time replaced the O2 sensors. I am not getting Code 43 or 44. As I am not driving her daily I don’t have a good idea what the gas mileage had dropped to. So I decided I’d spend the money and replace.

I bought the Denso brand this time. They were slightly higher than the NTK’s. I also read online that Denso was a leading brand, so why not right?

The replacement is easy. You need a 17mm open end wrench. Hopefully someone put the copper grease on the last time they were swapped. This magical glittery goodness prevents rust welding/corrosion.

The driver side sensor is best reached by working from under the vehicle.

Pro-Tip: as you are banging your wrench underneath wear eye protection or enjoy the dirt that will inevitably be in your eyes.

Here’s a pic of the old sensor. It has quite a bit of muck on it.


Disconnect the plug before starting the wrenching.

Apply the copper grease to the threads of your new sensor.


And replace.


Now its time to connect the plug. I’ve gotten to be a big fan of dielectric grease. So I bought this pressurized tube. Pull trigger grease comes out. Nice.


Here it is applied. It will assist in keeping water out of the connection. The engine gets so hot that I bet water doesn’t stay long in the plug…but I thought it can’t hurt.


Reconnect. Repeat on the other side. The passenger side is easier to get to. You can do that side from the top. No pictures…you’ll have to take your own.


You can see the old sensors are looking pretty knackered. I put them in a box and added them to the on-board spares box.

I fired up the old girl and she idled nicely at 500-600 rpms. I did notice the Check Engine light came on again. I looked at the code and it was the fuel rail sensor code, Code 14 – Coolant sensor. You can find the codes on JE Robison’s site. I looked at the location for the fuel rail sensor. The wires are bare and the plug is showing its age. I put my finger on it and the engine changed when I fiddled with the connection.


That’s going to need some attention. I’ll work on that this weekend. I wish I had a spare plug I could swap in. Its another thing to put on the list for the breaker’s yard.

This is an easy job its a 1 on the Difficulty Scale.

Good news, the shop goes up this next week. I’ll soon be working under cover. It’s been a long time coming.

Thanks for reading, and Happy Rovering.

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