Frustrating problem with 940 dying randomly. Only dies shortly (1-3 miles) from a dead start. This is summer time in Tennessee. 90 degrees. Car will restart after a few minute rest. Like the old time vapor lock.

On diagnostic LED I get 223 (signal missing from idle valve error) and 132 low voltage error. I have removed and cleaned idle valve which looked very clean and seemed to be operating smoothly. Cleaned contacts. I replaced pressure sensor. I ran a can of injector cleaner through and throtle body looks good (sprayed cleaner anyway). Fuel pump was replaced somewhere in last 10k miles (used car, not totally sure of date) and fuel filter looks brand new...still shiny..so I suspect stlling problem is persstient. I have looked at ground wires, checked battery voltage at load, cleaned terminals, etc. looked at vacum lines, checked most of the codes on the computer identified in Chiltons manual (Pump relay indicates good).
Clear the codes and then after it dies (randomly) I get these same two codes.

Where to look next? What could be causing this combination of errors. Perhaps coicidnetally the spedo has become erratic. Replaced sensor with junkyard part and didn't get any better, maybe worse. Could these be related?

Any advice on how to

Hi, well having had sometime to think about your issues, i would start by looking at the alternator. You mention you have a 132 fault which can mean either TOO high or TOO low voltage, the 223 is as you know is idle air valve signal absent or faulty.

I would say if the rectifier or voltage stabaliser has failed within your alternator this would bring up faults like these. Can you try another alt just to prove if its that or not.

What is the max voltage, with NO load that your alt gives ?

Keep us posted on your findings

Regards

AF

Will try. Can I test/ verify this somehow without replacing alternator?

Is alternator same for all b230f engines? Local junkyard has 960 and plenty of 740's but no 940s.
Thanks for thinking about this. Intermittent problem. Doesn't occur every trip, but when it does, it typically only dies once then it runs magnificently the rest of the day.

It is an older battery, but seems OK: Voltage at battery terminals: Engine off: 12.2v at rest, 11.6v under load (headlights, blower, radio). Engine on: 13.8v no load, 13.22v under load. If I need to test elsewhere please let me know. I did make sure alternator connections are very clean and ground to engine block is clean and sound. Wire under engine 'appears' in good shape, but haven't tested electrically.

I appreicate your help. THis is my first volvo and I am learning every day

yes, i have a 740 alt on my 940. thats a B200 and a B230, all should fit, depends on the accesories fitted like a/c etc, coz the mouting position is different - but with a bit of modifying these can be made to work ok. Your voltages appear to be not far off, tho would expect a little more on engine running no load test. 14 would be about max, tho your regulator will max out at 14.5.

AF

So do I still need to replace alternator?

Its always difficult with faults like these as often its a process of ellimination, which can start costing quite a lot as the fault tracing process continues.

I`m fortunate as I have pretty much a full cars worth of spares that i`ve collected over the years, but i realise not everyone can do that.

If at all possible, try and BORROW an alt from someone, this will help to keep the costs down whilst we find the problem.

I have just carried out the same tests as you did and these are my readings:-

Battery off load - engine stopped = 12.33v
Battery on load - " = 11.43v
Battery off load - engine running = 14.27v
Battery on load - " = 13.75v

All on load test have headlights on main beam, all heaters on, demisters etc, infact everything electrical to be switched on.


AF