03 Tahoe knock sensor code
We have a 2003 Chevy Tahoe with a 5.3 V8 engine. We recently got a check engine light for a knock sensor. The message on the scanner was "Knock sensor reading low voltage". I have read about this problem a bit and it seems like the harness inside the engine, rather than the sensor itself usually fails and causes this problem.
This repair apparently involves removing the intake manifold, and this is a job we'd rather not have to do on an occasional vehicle. So I also read that this sensor could be bypassed with a `100 ohm resistor. This would run the car in "limp" mode. I don't really know what that is but if it is just a small loss of power I didn't think that would be a problem for something we would just use to bomb around town in. So we unplugged the harness from the engine and plugged a 100 ohm resistor into it. We taped it up well and pushed this wire into a tight grounded metal can. I read that the sensor, or rather I think there are two of them in there are piezoelectric sensors that will develop a very small voltage across them when they "hear" what is the beginning of a knock.The timing is then adjusted by the computer accordingly. This was the way I understood it anyway. I figured with such a small voltage, keeping the modification grounded would shield it from the electrical "noise" of the engine. We reset the code and started the car. The check engine light came back on and a message I've never seen on the dash appeared: "reduced engine power". The car had no power, would not accelerate, and we had all we could do to just get it back in the driveway. Now up until the time we made this modification even though we had the code there was no loss of engine performance noted. We just had this code that prevented us from getting a sticker. We haven't yet tried to plug the harness back into the engine to see if the power returns. Is anyone familiar with this problem? Am I bypassing this nuisance sensor adequately? We're not going to take any trips with this car. It's just a second car and will be used by my wife to get the kids around town. As I've already said, it's just a second car and we'd really just like to be able to use it. If anyone can please help me to get this thing to run half way decently without having to do this engine repair job, I would be very grateful. Lenny |
03 Tahoe knock sensor code
> wrote:
>We reset the code and started the car. The check engine light came back on = >and a message I've never seen on the dash appeared: "reduced engine power".= > The car had no power, would not accelerate, and we had all we could do to = >just get it back in the driveway.=20 This is why they call it "limp-home mode." >Now up until the time we made this modification even though we had the code= > there was no loss of engine performance noted. We just had this code that= > prevented us from getting a sticker. We haven't yet tried to plug the harn= >ess back into the engine to see if the power returns.=20 The sensor is giving an error. As long as the engine never knocks, it doesn't matter. But, the engine may be damaged if it ever does, because the ECU might not know it, and won't be able to do anything about it. Putting it in limp home mode will probably prevent engine damage, but as you noted, it won't be very drivable. >Is anyone familiar with this problem? Am I bypassing this nuisance sensor a= >dequately? We're not going to take any trips with this car. It's just a sec= >ond car and will be used by my wife to get the kids around town. As I've a= >lready said, it's just a second car and we'd really just like to be able t= >o use it.=20 If it's a disposable car and you have plenty of money to buy a new car when the engine is wrecked, there's no reason not to keep driving it as-is with the check engine light on. It'll probably be fine, but then again it might not be. If you would worry if the car just up and died all of a sudden, then fix it. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
03 Tahoe knock sensor code
Scott Dorsey wrote:
> > wrote: >> We reset the code and started the car. The check engine light came back on = >> and a message I've never seen on the dash appeared: "reduced engine power".= >> The car had no power, would not accelerate, and we had all we could do to = >> just get it back in the driveway.=20 > > This is why they call it "limp-home mode." > +1 when the effort to get around a problem exceeds the effort to just fix the problem, it's illogical to keep going in that direction. GW |
03 Tahoe knock sensor code
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03 Tahoe knock sensor code
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03 Tahoe knock sensor code
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