'99 S70 AWD Coolant Sensor Light

[OberonXIV]

I've been having an odd issue with my S70's expansion tank level sensor. I recently replaced one that went bad with an OE unit I bought from ipd. However, now the light will stay on for about a minute after a cold start. Putting it into drive and inching forward a bit will make it go out instantly, but I like to let my car warm up for 30 seconds to a minute before heading out. It should be noted that this behavior doesn't happen if the cars only been off for a couple hours, but leaving it off overnight will cause this behavior to happen. There's no coolant leaks, and my fluid is topped off to the proper levels, so I don't believe it's a lack of coolant. The only idea I had is that it may be due to the fact that my driveway is on an incline, but testing this shows that the light stays off if the car is restarted. It's only a mild annoyance at this point, but I'd like to fix it if possible. Thanks for the ideas.

[scot850]

It could be as you mention your driveway is on a bit of a slope. The coolant tanks have a narrow cylinder the float moves up and down in. As the bottles get older, it could be there is a build up in the cylinder it runs in and it tilts and gets stuck on the side until you move the the flat.

Once the car is on the flat, and the header bottle/coolant tank plastic warms up it might open the cylinder up slightly preventing the light coming on. Perhaps removing the tank and the level sensor from it may allow you to look inside the tank through the level sensor hole and see if there is any build up on the sides. Clean with something like CLR on a cotton but may work.

It could also be the sensor has a little variance on sizing. It may be allowing the level weight to rotate sightly on a slope when the car is parked and it gets stuck until you move.

Neil.