O2 Sensor Intermittently Throwing Code
Thread Starter
Burning Brakes
Joined: Mar 2008
Posts: 1,073
Likes: 8
From: Houston TX
O2 Sensor Intermittently Throwing Code
Last weekend I was driving in a parking garage and drove over what can only be described as a diamond-plated expansion joint. It had a shallow break-over angle and I heard something smack the bottom of the car reasonably hard while I drove over it at ~5mph.
Something didn't quite sound right afterward. I took it to the mechanic the next day and he put it on the rack and there was a dent at the front of the resonator and it also had a small hole in it where the metal had torn. (FYI: this is my 3week-old Borla system we are talking about here
)
Long story short, he was able to use pliers and a hammer to bend and seal off the small hole.
Now to the point of this thread: the check engine light had come on shortly after the incident and gone off on the drive home. It threw a code for low voltage on the passenger-side pre-cat O2 sensor. Since it only happened once my mechanic said don't worry about it.
Today on the way to work the light came on again. I drove it to the parts store at lunch and had the code scanned, same code (the light had turned off again before I got there)
The low voltage code would indicate that it might not be the sensor itself, but instead the power supply. It also seems more than a coincidence that this first happened right after the impact on the exhaust system.
Anyone have an idea about this? Could the impact that jerked a wire loose? Things looked OK underneath when it was on the rack, although I was focused on the resonator and didn't look at too much else.
FYI: It's a 1996, so it has 4 sensors
Something didn't quite sound right afterward. I took it to the mechanic the next day and he put it on the rack and there was a dent at the front of the resonator and it also had a small hole in it where the metal had torn. (FYI: this is my 3week-old Borla system we are talking about here
)Long story short, he was able to use pliers and a hammer to bend and seal off the small hole.
Now to the point of this thread: the check engine light had come on shortly after the incident and gone off on the drive home. It threw a code for low voltage on the passenger-side pre-cat O2 sensor. Since it only happened once my mechanic said don't worry about it.
Today on the way to work the light came on again. I drove it to the parts store at lunch and had the code scanned, same code (the light had turned off again before I got there)
The low voltage code would indicate that it might not be the sensor itself, but instead the power supply. It also seems more than a coincidence that this first happened right after the impact on the exhaust system.
Anyone have an idea about this? Could the impact that jerked a wire loose? Things looked OK underneath when it was on the rack, although I was focused on the resonator and didn't look at too much else.
FYI: It's a 1996, so it has 4 sensors
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
The front sensors control the A/F mixture and fuel trim numbers. I believe the rear O2 sensors are just a check of the actual operation of the engine performance. I would start getting the specific code for the O2 which might give you exact location of the problem one and what might be the reading.
Thread Starter
Burning Brakes
Joined: Mar 2008
Posts: 1,073
Likes: 8
From: Houston TX
The front sensors control the A/F mixture and fuel trim numbers. I believe the rear O2 sensors are just a check of the actual operation of the engine performance. I would start getting the specific code for the O2 which might give you exact location of the problem one and what might be the reading.
