Melted loom causing P0131?
Thread Starter
TECH Regular
Joined: Oct 2003
Posts: 409
Likes: 0
From: Miami, FL
Melted loom causing P0131? I'm getting a P0131 - Ho2s circuit low voltage bank 1 sensor 1. I checked my driver's side o2 and found that the harness loom was touching the header. The loom melted away, exposing the wires, but they seem to be in ok shape. They aren't melted together that I can see and the insulation is intact. My question is whether proximity to the header can cause a P0131 code... can the insulated wires being so close to heat throw things off?
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
yes, that is most likely the cause ... be glad you didn't go all the way through or you'd be seeing tons of SES lights (if they go all the way through it'll blow the engine sensor fuse and you'll run open loop speed density all the time) ... remember ... heat = resistance ... more resistance = less volts through a wire
Try wrapping it up and tieing it away from the header, clear the code and see if it comes back... also watch that O2 sensor to see if it's still switching fast enough
Try wrapping it up and tieing it away from the header, clear the code and see if it comes back... also watch that O2 sensor to see if it's still switching fast enough
Thread Starter
TECH Regular
Joined: Oct 2003
Posts: 409
Likes: 0
From: Miami, FL
I replaced the harness (it was an o2 extension,) wrapped it in double thick heatwrap, and ziptied it away from the header. Started it up and a little while later the MIL turned off, so it seems that was the cause.
Thanks for the advice horist... I monitored the o2's and they seem to be switching fine, we'll see if anything changes once I drive it for a while.
Thanks for the advice horist... I monitored the o2's and they seem to be switching fine, we'll see if anything changes once I drive it for a while.
Thread Starter
TECH Regular
Joined: Oct 2003
Posts: 409
Likes: 0
From: Miami, FL
It's back... towards the end of a 6 hour drive today, the car started stuttering and bucking, then threw the same code. It had been fine for the first ~5hrs, then it started acting funny after stopping for a few minutes at a rest stop. It bucked for a few mins at most then smoothed out... I wonder if it's just a really slow-switching o2?
TECH Regular
Joined: Apr 2003
Posts: 413
Likes: 0
From: Atlanta, GA
Before I switched to vette rear's for my front O2's I used extensions which used a cheap loom that wasn't heat resistant. Needless to say it started touching the header and eventually burned all the way to the wires. I found all of this out by watching the scanner as my car barely would run when it touched the header. The O2 Millivolts went constant. It never moved I believe it was @ 1 volt all the time on the front driver side O2. I went under the car and found the burned wire and replaced both of my o2 sensors with the longer ones which also had heat resistant wrap on the wires making it less vunerable to heat damage. It never actually posted any O2 codes just misfire codes as it couldn't keep itself running. The symptoms felt like some of the coil packs quit firing temporarily when I hit a bump or the engine happened to move in the right spot.
Thread Starter
TECH Regular
Joined: Oct 2003
Posts: 409
Likes: 0
From: Miami, FL
The light turned itself off today. I didn't make any changes or touch anything, it just went away. From what I'm seeing by doing a search, this could be trouble.
For anyone who cares to help, I have older Grot longtubes.
For anyone who cares to help, I have older Grot longtubes.
