Exhaust Emission Sensors - anyone else having issues with them?

[JimC]

In August I had to have the emission sensor on the driver side replaced - I was driving home from a day at Gingerman and the CEL tripped. I believe it was the downstream sensor that time.

Then about 6 weeks ago I had ANOTHER one this time on the passenger side. Once again, CEL for exhaust emission sensor, downstream on the passenger side. They replaced it but said that they had trouble resetting because the upstream sensor was also showing signs so had to order an upstream sensor. That got replaced last week.

All was fine since Thursday last week.

Until yesterday, driving home and ------ CEL for exhaust emission sensor reading AGAIN! I am calling the dealer to get it back in once again to find out which sensor this time.

The only thing that I can think of that has been a triggering event before each of these is washing the car. In all three cases I ran the car through a wash to get the underside cleaned. So it sprays up under the body. In August to get track junk off the underside, and the last two to have it spray to get road salt off the underside. Maybe these sensors aren't sealed properly and water gets in and grounds them out?

Has anyone else had issues with these emission sensors?

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[Mastermind46]

I have not seen any issues reported with the O2 sensors. I also used my underbody sprayer and haven’t had an issue. I can’t imagine you have received all of the faulty ones though.
Are the sensors reading poorly or completely non functioning?

 

[Skye]

I think there's a few things going on.

The force and amount of water isn't doing the connector any favor. The connections are designed to work in wet weather and general road spray, but it seems the wash might be doing more than that.

Salt is an electrolyte; it's capable of passing an electrical charge or interacting with an electrical circuit.

After getting this current sensor issue repaired, I'd refrain from getting the underside sprayed at that car wash. People do use general wands, hoses and other items to clean underneath. Maybe study what this current washing system is doing and manually clean the underside with something less intrusive.

 

[JimC]

It keeps coming up that they are showing "an electrical concern with one of the exhaust emission sensors".

All three times it happened after I used a car wash with underspray. In August it was the driver side rear sensor. That one stayed reporting for about a week before they got it in and then the CEL went out the day the took it in. But they replaced it.

Then the passenger side rear tripped 6 weeks ago, after getting underspray done. It stayed on for the 5 weeks between diagnosis and when the new sensor arrived and they replaced it. That time though it showed the front sensor on the passenger side was reporting a pending report as well. So they ordered that one and replaced it last week.

Then on Sunday I stopped to run it through to get the underspray done to clean the road salt off. Stopped to gas up, and the sensor tripped a CEL again. Not sure which side because the Ford Pass App doesn't tell me which side or which sensor, just the generic report.

This morning though the CEL is off. Which is suggesting to me that it may be water intrusion into the connectors when I do the underspray cleaning, causing it to short out perhaps. It is scheduled to go to the dealer on Tuesday so I told my wife I am going to run it through for an underspray this weekend and see if the CEL trips.

 

[JimC]

I think there's a few things going on.

The force and amount of water isn't doing the connector any favor. The connections are designed to work in wet weather and general road spray, but it seems the wash might be doing more than that.

Salt is an electrolyte; it's capable of passing an electrical charge or interacting with an electrical circuit.

After getting this current sensor issue repaired, I'd refrain from the car wash.

The only issue with that is I drive year round and with road salt like to get it cleaned off! It seems that the sensors should be able to handle the spray. I've never had a car give me an issue in the past. My wife's Lincoln goes in every week, with underspray, and has never had an issue.

 

[JimC]

It looks like this is finally figured out. I scheduled the car back in again after it tripped the CEL once again with the underspray. A couple of days later the light went off, after I was able to accelerate getting on the highway at WOT up to a little over 80 mph. The Saturday before the appointment I tested the underspray theory and it popped the CEL again.

So I gave the service writer this new information regarding the trigger - which suggests some wiring issue is involved.

They had the car for a day and asked to keep it longer for more testing, and gave me a new F150 as a loaner. They thought that it was the catalytic converters and were discussing replacing them with Ford. More testing was requested by Ford before agreeing to spend that much money and then I left on a week long cruise (they told me to keep the loaner). So they had almost 2 weeks to check things out this time.

In the end - they found the wiring harness was rubbing on a spot and had worn through. So with the underspray it was shorting out and when it dried out enough it would be fine - time and warm weather or aggressive acceleration would dry it out apparently.

Although I did test it with an underspray to be sure.

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