'95 LeSabre, 250K, runs great. Check engine light on randomly and signs point to a computer malfunction causing the light to come on. Is it true that only a dealership can replace the computer, not an indy mechanic? How much for the repair? Will it run ok w/o a new computer? Thanks.

Are you sure the ECM is faulty? What are the codes? There is no way the car runs great if the ECM is faulty. The ECM controls the engine, and a faulty one will not run the engine well at all.

And, no, it is not true a dealership is the only place to have it replaced. On a '95 Buick, the computer may or may not be VIN-coded, but the OBD-II system is not valid, so VIN-coding is not a requirement. These computers are on sale all the time through my parts supplier. They do need the VIN number to match up all the options the ECM is programmed for. Then, it is a simple plug-in installation. Pulling a salvaged one from a car that has the same options is just as valid.

Replaced the throttle control module six weeks ago because of high idling. Four weeks ago the code said faulty EGR valve, so replaced that. Yesterday, put a new throttle control module on, thinking the replacement one was faulty. Check engine light continues to randomly come on as it has for a few months. I like my mechanic but it sounds like time for a second opinion? Hard to decide when it is time to give up on a car.

You should start by checking the harness and the grounds for the ECM…

Interesting. I will have someone do that - I am not handy enough.

Constantly changing codes is probably due to a defective computer. I think that anybody can change a computer on a 95.

Often people make the mistake of assuming that codes tell you that parts are bad (like ERG valves or throttle controls). But the computer can’t really tell if a part is bad. It just gets readings out of systems and points to system problems. A lot of what is involved is the control circuits for these systems and a lot of those codes indicate circuit problems. With something like the EGR system there are several different parts that need to be checked. Anyway…you just might be having that typical problem where people think codes mean that you replace the part named in the code.