95 940 turbo will not pass emissions 2-3-1 trouble code?

[cquarts]

for the first time in 14 years the car will not pass emissions. it still runs like a new one but the 2-3-1 code reoccurs after i clear it. i always check/clean/change or do everything that would affect the emissions test before i go for it. do i need a new oxygen sensor since this code is saying something about it? what about the cat convertor? the check engine light has never come on. bill addressed the code issue when i had a slight hesitation at start off and clearing the code temporarily solved the accel issue which, of course, may not be related to the emissions issue.

[billofdurham]

Unfortunately 2-3-1 only covers fuel trim and is not specific about whether the trim is lean or rich.

Some of the checks to be done, according to VADIS, are:
Lean trim - Air leakage
Low fuel pressure
Faulty sensor signals

Rich trim - High fuel pressure
Contaminated engine oil (fuel)
Leaking injector
Leaking canister purge valve
Faulty sensor signals
Leaking exhaust sytem

Another reference I have, which will remain unnamed, also calls for checks on:
Heated oxygen sensor
MAF sensor
ECT sensor (not the one for the gauge)
This is for both lean and rich trim.

Bill.