ikindawantabronco

Hi all-
Proud owner of a beautiful 95 (5.0 L V8, automatic), will post pictures so I can justify bragging about her.

I'm under 200k miles, third or fourth owner.

Everything runs beautifully, recently changed thermostat to 180F so she runs a lot cooler; makes road trips much more fun (even though I still drive with the heat on full blast and windows down).

Only issue is that the O2 sensor goes out every 6 months or every drive longer than 2 hours; I always just head to the nearest O'Reilly's and present them with the receipt from the last time that I keep in my glove box, spend a buck fifty on anti seize, and change it in the parking lot trying not to burn myself too badly. Three year warranties are pretty great.
I've been doing lots of research because I want to figure out why, but I'm not getting any results as to why. Thoughts?

Steve83

Define "goes out".

ikindawantabronco

Acceleration gets goofy, idle is super uneven, check engine light comes on. Change the O2 sensor and it's all fixed for another six months or so. I've read that it can be caused by running rich or by using cheap gas (I'm a poor college student so the low octane is my automatic choice).

Steve83

That's not a diagnosis (or even an indication) of a failed oxygen sensor (HEGO).


(phone app link)

What brand, PN, & source is the current replacement HEGO? I highly recommend switching back to the original (if you still have it) or a new MotorCraft (from Amazon, eBay, or wherever) AFTER you find & fix the real problem.

What is the fault code(s) stored when the CEL comes on? Click this & read the whole caption (it's LONG) before attempting to read codes:


(phone app link)

But don't buy or replace anything just because it's mentioned in the code definition. Codes are not diagnosis or shopping lists - you still have to find the root cause before you can repair it effectively (& cost-effectively). If you don't have one, buy a Haynes manual & read it:


(phone app link)

ikindawantabronco

Hi Steve-
I actually haven't ever checked the code... my dad literally just told me that's what I need to do when I have that sort of issue.
Thanks so much for the resources- I'll let you know what I find.

Steve83

If your dad isn't a professional mechanic, then his guess is no better than yours or a neurosurgeon's.

ikindawantabronco

He's not a professionally trained mechanic, but he has been working on cars, trucks, cranes, and pretty much anything else on wheels and in construction that you can think of for the past 25 years.
The previous owner, who is a professional mechanic, and works on this truck with me sometimes, said that switching out the O2 sensor is what he always does for this too.

I'm just looking for other opinions, because admitting my truck just likes to pitch a fit about road trips doesn't sit well with me, if you can imagine.

And also, making O'Reilley's buy me a new O2 sensor a couple times a year until March 2020 when the original warranty expires does make me a little guilty.
Switching it out instantly fixes all the acceleration and uneven idle issues. And the old sensor itself looks pretty rough, so it wouldn't surprise me. I'm just keeping a 7/8s crescent wrench in the glovebox until I figure out what's actually going on.

Steve83

OK. Go back to post #4 and do each thing I suggested. Report your results.