Service Engine Soon Light - changed battery

The flashing SES light indicates that the PCM is detecting a catalyst damaging missfire. Perhaps a rodent or such has chewed thru a wire during storage?

The SES light can indicate many things; I need an OBD tool to see if there's a code. A rodent? That's a possibility, but the van was parked in an outside storage parking lot. I've been parking my trailered boat in the same lot for several years when it's not in the water, with no problems

Like Neil said, a flashing SES light indicates one thing a catalyst damaging misfire. Bob

A flashing SES light means but one thing; a catalyst damaging miss fire is being detected by the PCM. That doesn't necessarily mean that there really -is- a miss fire, but that is what the PCM is trying to relay. And yes, you'll need to scan for trouble codes as an early step in diagnosis. I'd also look over all the wiring underhood for any signs of rodent damage.

Rodents may find automotive wiring more tasty than boat wiring.

Follow-up: I went out to buy a code reader today but the Service Engine Soon light is no longer lit! (The light bulb works - it comes on when you first turn the key to the on position.)

Well, took the van for service (lube and a filter change) the next day and the SES light didn't come on. It's been several days, and it's still off. Whatever it was. . . . My motorhome is also a Chevy (3500) with a VorTec V8. It seems that when going up a hill that's steep enough to cause the transmission to come out of overdrive and then shift down to second, resulting in high RPMs, the light comes on. It's happened several times. First time the code was for random misfires. The tech said there wasn't much he could do: he cleared the codes, the engine ran good, and the codes didn't come back. Second time was on a Saturday afternoon in the desert in AZ. Couldn't do anything about it on the weekend, and everything seemed OK, so I kept driving. The light went out on Monday and stayed out until two months later. Again, the first big hill that meant downshifting resulted in the SES light coming on. Had it checked: same thing, and once cleared the codes stayed away. Two days later, another big hill and the SES light came on again. It went away after a couple of days. I hate to risk getting complacent, but this is frustrating.

"Jim Garlington" wrote in message news:ZWSdf.15040$ snipped-for-privacy@tornado.texas.rr.com...