bearca

The gas mileage on my 97 Max isn't very good, from reading posts on this forum, sounds like it could be a faulty knock sensor.
Will a faulty knock sensor light the check engine light. The light is not on.
Is there any way to check the sensor.

Thanks

niznos

A bad knock sensor will not trigger the "check engine" light. It's a phantom code. If you run a diagnostic code check, it will show, but it does not turn on the check light. You must run the codes to be sure on this one.

When mine was bad on my 98, the mpg was in the teens, and lacked power under 3000rpm.

Places like Autozone will run the codes in hopes of selling you the sensor. Could start there.

Exalta

uhm so do i have to replace the sensor if that happens?

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niznos

Well, it depends on what you mean by "if that happens." If you get a code showing a bad knock sensor, then yes, you must replace it. The car will continue to run with a bad sensor, but it will add fuel and retard timing to prevent knock that it can no longer detect. You will just have to put up with bad MPG and performance.

FYI, most (if not all) service manuals will tell you to remove the intake manifold. The intake manifold obscures the knock sensor. There is a way to replace the sensor without doing that. Trust me, you don't want to take the manifold out if it's not absolutely necessary. I can't recall where some step-by-step instructions are on the net, but it's out there. Do some searching around and you will save yourself a lot of time on this service.

Good luck.