OBD2 can't connect to ECU
 

I have a 1997 940 Classic. I have the check engine light on and I got a a used cheap OBD2 reader (ANCEL AS200). I connected it to the car and I get an error saying it couldn't connect to the ECU.

Should I look for a unit with a specific protocol, or what? I was still at the sellers house, so I didn't buy the reader. But now I don't know if it's worth getting one from amazon either!

EOBD, the EU friendly OBDII standard, only became mandatory in the EU in 2001 for petrol cars, so yours will be some kind of older protocol, possibly 1 or 1.5. One of the RWD boys will be able to advise in more detail.

None of them will work so don't waste any more money. Look up Loki on here as he makes a reader for your car.

Oh ****... Going to a mechanic he won't be able to read it either? I'm in a hurry. Anual inspecting is due in a few days :(

Pull fuse #1 (engine off) for 30 seconds or more then refit it.

Take it for a test drive and note when/if the EML comes back on.

Mark is absolutely correct, it's a "not-quite-OBD" port on the 940s and will only work with a dedicated code reader - or a 12V LED (NOT a bulb! :nah: ) and a piece of wire but you need to know where to plug it in, which is the reset line etc - Lokis reader does the hard work bit of this in a conveniently fully built/tested package with an OBD plug on the end


No, the mechanic can't read it with his stuff either. :nah:

Thx. I'll do that to see if it stays off. I "know" what prompted it in the first place. I washed the engine bay because I wanted to slean it a bit before I removed the PCV to clean it. Water must have creeped into the plugs or distributor or whatever. Car never stopped, but was idling poorly afterwards (yesterday). Today it runs better but not quite there. I wanted to read the codes before starting to find out on my own what's wrong. But it won't be that easy I guess.

This is how it looked and sounded yesterday: https://youtu.be/49FTRI3dCBs

See how it goes tomorrow after pulling and refitting the fuse. The problem with reading codes after getting the HT leads damp is you will read codes generated by the ECU that doesn't know what a wet plug lead is, just sees things not happening as they should.

For example, a blocked fuel filter can trigger a MAF code to be generated, as can running out of petrol because the ECU always assumes perfect conditions. It's not intelligent enough to realise the car is out of fuel and as a result there is no fuel to give the required engine speed increase the ECU has called for so it assumes the MAF isn't reading the increased airflow demands made by the EICV opening when the ECU tells it to.

Just one example of a red herring! :thumbs_up:

I know what you mean. But on a car that's easy to check, obd2 compatible, you lose nothing by checking it.
Well, with that trick I will at least be able to pass inspection don't you think? That's my most pressing issue.

OBD-something Code reader
 

As other posters have noted, I do make a suitable code reader. I don't like to push them, preferring to let people who've bought them from me do the talking.

The 940 appears to use a Volvo-specific protocol rather than even OBD-I; I had an RAC patrol try, and fail, to read the Valdez's fault codes once, and he had a lap-top with OBD-I software installed.