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Causes of melted O2 sensor?


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Pic added!

 

I've been looking for a vac leak for quite sometime to no avail on my 07 LGT< about 70k miles. I thought I had it ironed out, but getting an etune as soon as I pulled a LV the fuel trim was sky high. Back to searching for a leak. Got fed up, took to the dealership. They called to say an O2 sensor had it's tip melted, which was confirmed by the sales guy I know texting me to let me know that thing is fried.

 

Besides being plowed by the cost (and didn't even buy me dinner first) I am just wondering of the potential cause of this? I want to make sure to do what I can to prevent in the future. Clogged/failing cat? Just too much awesome pumping through the exhaust? :)

O2.jpg.a35fea8c13cd133fcc23ecd456f43e27.jpg

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Overheating an O2 sensor is "interesting". Not impossible, but I can think of a few possible causes:

 

  • Bad Exhaust Gas Temperature (EGT) sensor - if it isn't working it doesn't detect a high temp condition and therefore appropriate action isn't taken by the ECU (richer fuel mixture etc.)
  • A changed exhaust or intake without a tune.
  • Injectors in need of maintenance.
  • An air leak somewhere in the system (both intake manifold and exhaust)
  • O2 sensor itself has been reporting the wrong value causing a loopback problem to escalate.
  • Bad valve. (Check compression and valve clearances)

And the cat may also take a beating if this has happened.

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Hmmm ok thanks for the info.

 

Prob not the cat since I just pass a smog a few months back.

 

My MPG did drop over the past 6 - 8 months, so it seems the O2 sensor was slowly going out. Still no CEL up to this point as well.

 

Once I get the car back I'll take it for a drive and pull some logs to see if there are any changes.

 

All stock, no mods of any kind. So exhaust/intake are out.

 

Vac leak - possible. Though I've gone over everything and can't find one, will have to check trim level and see if there is an issue.

 

Any way to test the EGT?

 

 

Injectors/valves/compression I'll have to get checked.

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How bad wasthe cost of the O2 sensor ? I gather it was the front one.

 

I just replaced the front O2 on my wagon with a OEM one. It was like $130 with tax after my discount. I think retail is like $160.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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I'm guessing if the MAF is bad and sending bad info to the ECU, that could cause issues.

 

I'm surprised you didn't get a CEL.

 

Hey, at least the car is fixed and you can enjoy driving it.

 

Spending a ton of money on these cars seems to part of the norm now.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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Cars been owned free and clear for well over a year now and I haven't spent much $$$ on this car so far, since I've done most everything myself. So it balances out. Fingers crossed the MAF and O2 clear up my fuel trims and I can get my Cryo tune going. Have already held Dave up for too long on this and I'm sure he is getting tired of my email updates. :)
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Good Luck. :)

 

I'm about to spend more money on my wagon soon. Like a idiot I went and opened the GB forum. What do I see... Mike has a GB for sway bars....damn him.... :)

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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Good Luck. :)

 

I'm about to spend more money on my wagon soon. Like a idiot I went and opened the GB forum. What do I see... Mike has a GB for sway bars....damn him.... :)

 

Great. I both love and hate the fact that you pointed this GB out. Sway bars are on my list for the future, but I'll probably kick myself if I miss out on this.

 

My wallet is displeased (but it'll get over it).

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