I've got a 93 LS400 with 175K miles. It's been fairly well maintained and runs great. Out of the blue it suddenly ran rough with check engine light on starting it. It would engage and drive but with little in the way of power, we're talking a quarter of the pedal would slowly get you up to 15 mph. Idle was rough and after 5 minutes it shut off on its own.

My shop looked at it and said the code it is throwing is for the control computer - the device that generates the code. So they cannot be sure that replacing it will fix the issue and even used the parts are pricey. I think the car is worth the cost but of course don't want to throw such an expensive part at it if I don't have to.

Does anyone have experience with a failed control computer? The only other piece of evidence I have is that the car did suddenly die at interstate speeds about a month ago but I pulled off, restarted it and it ran fine until this recent issue. Thanks in advance for any help.

 

Talked to my mechanic in person. He confirmed that the code is for the computer itself and is looking for a used one for me as they are expensive. The loss of power was the car starting in a high gear due to the malfunction (limp mode perhaps?). Still he cannot guarantee it's not the computer but believes it is.

Strangely he reset the codes and it runs fine now but it could fail again at any moment in my opinion and given its recent behavior I want to replace it....