Check engine light has been on for a while...finally decided to pull the codes because I have been getting HORRBILE fuel economy lately. Also, if the car is hot and I try to restart it I have to have my foot on the gas to keep it ideling. Here are the codes:

LH 2.4:
1-2-1 (Faulty AMM signal)
2-3-1 (Fuel trim rich/lean)
1-3-3 (Throttle Switch idle setting faulty or ground fault)

Ignition:
2-3-4 (Throttle position switch idle signal faulty)

I cleared the codes and started the car, and the check engine light stayed out for now. Even so, something is causing poor mileage. When I was under the hood I also ran the mode 2 diagnostic test on the throttle switch and it seems that there is a signal being sent when I moved the throttle. Should I replace the AMM and TPS? Is this something I can do myself? Is it expensive? I am not looking to spend hundreds of dollars here, but I can't keep driving with less than 18 miles to the gallon. Thanks!

--Steve G. '89 740GL 233,000 mi

the AMM part itself is fairly expensive. it's supposed to be pretty easy to replace though. the TPS i'm not sure about the price, but i replacement is pretty easy to do as well.

this is assuming you're mildly handy with a wrench and/or screwdriver, and have the tools on hand. if you don't have the tools, might as well buy them and use them in the future too. :) i've found that tools are almost always a good investment.
--
Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

Are you anywhere near a boneyard and are you mecanically inclined?

I find that replacing parts like those that you suspect are defective on your car can be had for a fraction of the cost of a new one... (usually about %10 of new cost) I live in L.A. so there are several bone yards within 20-30 miles or so and lots of Volvos... Just pay attention to the Bosch part # on your parts and make sure you get one that matches... Owning a 10+ year old car can be very expensive if you don't do the work yourself....

jj