'99 Q45t Knock Sensor and EGR Valve Codes together

[richardvestal]

1999 Q45t with 120,000 miles.

Bought it used w/ extended warranty. Never had much trouble, except left headlight and the air conditioning temperature dial wanted to go in reverse. Thankfully, both were changed under extended warranty.

Just recently the "service engine soon" light came on. Autozone says it is both knock sensors and the EGR valve. I bought both KS before finding this website.

I am planning on doing this job myself. Just finished replacing the plenum gaskets on my sons 96 firebird and I feel up to it!

All the posts on this forum talk about changing the hoses and wireharness while under the plenum. I will do that. I haven't checked the availability or prices on these items yet. Do you know if these are availbe from parts stores or only the dealers?

However, none of the posts on this formum seem to talk much about the EGR valve. Is it possible that the EGR valve is causing the KS to show failure? Or visa-versa?

Should I change the EGR whil I am at it? The EGR is $165 from AutoZone.

Also, where can I get a FSH (field service manual?). I see posts talking about downloading one.

Many thanks!Richard

[jdm_master_X]

the EGR may be be plugged or stuck open, causing the intermittent detonation and the knock sensor to constantly compensate. definitely check your EGR before changing parts.

[richardvestal]

Dear X,

Thanks for your input. Do you know where the EGR is on this engine? I have always changed the oil, the battery, the wiper blades, etc., but I really don't have any documentation on where the details are located. I am guessing top rear of the block and that is where I will start looking.

Richard

[richardvestal]

Found a "free" download of the Factory Service Manual (FSM) on

http://www.phatg20.net/modules...query=

It appears that they have all models and years of infinitis.

Have to use another program from http://www.rarlab.com to extract the files after downloading them.

I see the EGR control valve is pretty much where I expected it to be. There is a detailed description of diagnosing the EGR in the FSM. I am going to give it a try.

Regards, Richard