Hi there guys and gals, thus is my first post :). Anywho let me give some background on my issue. I am the happy owner of a 1995 volvo 940 turbo with 177k miles on it. Anyway in the last 10k miles the following parts have been repaired or replaced. Injectors rebuilt by volvo, all new vaccum lines again by volvo, brand new throttle position sensor, new mass airflow sensor, new bosch ignition coil, new oem volvo spark plugs and wires, new fuel filter, and the timing belt was checked by volvo and is in good shape. Finnaly a new ac belt and irs been adjusted twice to stop from squeeking, and a freon recharge. Now my issue is I have a check engine light that occasional comes on. The csr runs perfectly fine no stalling no rough idle,but I can't check what the code is becuase my obd1 boxes A and B are missing quite a few of the metal pieces that the pin goes in to make the led blink. If I unplug the battery for 2 or 3 mins the code go's away and will stay off for at least 500 miles. Any ideas? Other than me going to a junk yard and trying to salvage a new obd 1 a and b box? Thanks in advance.

I think my first step would be too go to the junkyard can get the parts you need so you can check the basic codes.

The wife's 940 had the same issue. I would do the battery trick and the light would stay off for a period, only to come back.

Turned out on her 94 it was the EGR vacuum solenoid. Very expensive part, so I tried a swap of the same part between my 240 and 940.

This was a spell back, and I think I swapped them back and forth couple of times.. and at some point it just ceased to be an issue. No more ck engine light.

So what happened? Not sure, but I would bet it related in some way to ground points or the ECM adapting in some way... maybe just the unplugging/reconnection of the part a number of times cleared up corrosion.

The one thing that is critical on all these older Volvos... especially when we start just buying new parts with no real change..is to get the corrosion and ground points all corrected.

I still need to do it properly on all three of my bricks.
--
"Do you think that's air you're breathing now'? (The Matrix 1999) '94 940T (463K+), 92 245 (300K+), 90 740 (148k)

Thanks guys for the responses :) you have given me some good advice. Thank you

EGR?

Might be a dirty EGR valve.

How do I check that Mr Nabisco? Thank you :)