Once a Check Engine code is set you should start by resetting it. If it doesn't reappear in the next few days then it may have been a transitory condition (like a temporarily fouled O2 sensor). You probably already know the resetting procedures as described in this section of the 700/900 FAQ.

You mention a rough running engine. If it's rough at idle (very common with your B234F engine) then that's typically caused by a dirty throttle body (and/or dirty PCV or idle air control system). If it's rough at speed then it's more likely to be fouled plugs (or dirty ignition wires). The B234F is typically running at lower revs, especially in the city, and will easily choke up with deposits. There's a good chance you can clear your problem by simply giving it a good highway run with the revs up, staying out of overdrive, periodically dropping down into 3rd, with occasional bursts of acceleration (be warned, this may attract undue attention of nearby motorists and/or the local constabulary). Following that, take the throttle body off and give it a good clean as well as cleaning out the flame trap/PCV hoses and rinsing out the idle air control valve with carb cleaner or solvent. Clean and/or replace and properly gap the spark plugs. Read the plug tips and note if all cylinders are the same (tan is ideal, dark means too rich, oily black means there's engine wear or valve problems, white is too lean, ashy typically means there's intake deposits). Reset any OBD trouble codes. You may be surprised that your problem has gone away and the engine runs much more smoothly. My experience says you won't need to look further, but I'll ramble on as I may not see any follow-ups in this thread.

Now, despite what the FAQ says, my guide says 2-3-2 can mean either too rich or too lean at idle (that's for both your Bosch LH 2.4 system as well as Regina systems). In either case, the O2 sensor (as mentioned by the previous poster) is a suspect, although not necessarily the prime suspect. After resetting the OBD trouble code, note if the Check Engine condition reappears right after starting a cold engine. If it does then it's not likely the O2 sensor as it's ignored for the first few minutes until the vehicle is fully warmed up. You can do some basic checking of O2 sensor functionality with a multimeter -see this article in the 700/900 FAQ.

If it smokes or smells gassy out the exhaust then it's definitely too rich and things like the fuel pressure regulator and O2 sensor should be on your suspect list. The injectors and injector seals are less likely areas -running decent quality gas will normally keep the injectors from fouling and leaking and the newer injector seals last nearly forever. You could try running a few tankfulls with a quality injector cleaner additive (like Techron if you can get it). I would highly recommend you remove the plugs and clean them after doing this as there is often ash build-up on the plugs after injector cleaning (or celebrate by treating it to a new set of plugs). I found the older B230F's with the LH 2.2 systems used to thrive on the occasional injector cleaning while the newer systems, like your LH 2.4, don't seem to need it (at least as often).

If it's running too lean or still running rough at idle then you should be looking for unmetered air, i.e. a vacuum leak -typically a loose or disconnected hose attached to the intake manifold (check both ends, look for splits), a split in the main air intake tube (best to remove it so you can flex it for proper inspection), a leak around the base of the throttle body (typically when it's been off and the old gasket was re-used or a bolt isn't tight), a leak at the brake booster check valve, or a leak in the interior ventillation system pneumatic servos (plug the nipple on the manifold to isolate that).
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Dave -940's, prev 740/240/140/120 Never overestimate what little I know.