My computer won't talk to my EGR

I have a 93 Prelude with 216K miles. I really want to keep it running, but am trying to determine how expensive it will be to fix the following.

My mechanic says the ?EGR?, and the ?EGR Solenoid? are working fine, but the computer is not giving any command to send vacuum to the valve. My mechanic, who I trust, says he can’t fix it and that I need to take it to the dealer, who I do not trust.

The dealer will charge me a diagnostic fee to tell me what I already know. Then what?

Others will, so, I will ask first: Is the check engine light on? If so, what code is it? How does He know?

See if he can make you a deal on the engine computer. It shouldn’t be hard to install. Many people I talk to say not to get one from NAPA. Although I don’t know whether it’s true that they are problematic, it is enough to scare me away. Sometimes you save money by guessing what to do by yourself. Not always, but there isn’t always a computer that will tell you that it is nuts, or where the bad wire is.

I suggest you have the codes read and report back. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

Since this is a '93, it is OBD 1, and the scanners these stores use are for OBD 2 only. However, I found this procedure for obtaining codes without a scanner:

“Use a jumper wire in the 2 pin service connector. (There is a second connector with a 3 pin use for a scanner). You can then turn the key on and watch the code being flash in your dash panel check engine light indicator. On some models, a led light is used to flash the code instead and this led light indicator is located in the computer itself.”

Here’s the page:

I have a shop repair manuel in a .PDF formatt if you are interested in it for your car. If you are PM me or give me your email address and I’ll send it to you.

This could be as simple as a bad ground or a pinched/burnt wire. If you want to invest the money for a shop manual and a multimeter, you can find the ECM connector pinout, test the grounds for continuity, test between the EGR signal pin(s) and the EGR connector for continuity, and that will tell you if it’s an ECM fault or a wiring fault.

Or you can just take it to a more competent mechanic and/or the dealer, and they will do that for you.

LOL, PM? On this site?

This shouldn’t be much trouble to fix I would think.

If the wiring between the ECU and the EGR vavle has been checked to be ok and the valve works when power is applied to it directly then the trouble may be internally with the ECU. They usually are reliable but they can have problems. You may want to try finding a unit from a salvage yard and try it out. It shouldn’t be very much money to purchase. Probably less than a diagnostic fee from a dealer.