prescottn

My engine has always like all the other XB's I know of started up with a Blue coolant level light which I know to mean the engine is just not at optimal temp yet. Well, within the past two weeks the weather has been getting much colder here, and now when I turn on the car the light stays red for about a full 15 seconds after the engine has already been started and then goes to blue for about 3 min (which it's always stayed on for about 3 min since I bought it)

I was under the impression that the red indicator mean BAD! Anyone know why this may be coming on then going away at first start now?

andrewdustin

not sure, but you could have a bad thermostat that is not opening all the way or something. no way to check except to take the hoses off and look at it (not easy). hopefully someone else will chime in with another possibility.

vettereddie

Mine comes on red for maybe 3 sec sometimes. It's not the thermastat, that's mechanical and not wired to the dash. it may just be normal behavior, your engine isn't overheating in the first 15 sec of startup. it may be a bad water temp. sensor. Even though we don't have a gauge, it does read and go to the ECU, you can venn get a temp. reading with the scan tools. It's easy to replace if it is bad, just screws in to the side of the block, you may need to remove the stock air box to get to it though.

Are you getting any check engine lights that would indicate the water temp sensor throwing a code? If not, I wouldn't worry about it. The thermastat will still work even if the sensor doesn't.

andrewdustin

^i was suggesting that the thermostat might not be opening all the way and there fore causing the engine to run at a high temp. but like you said it could be the sensor itself.

prescottn

I haven't gotten any CEL's in about 3k mi. I got a few of the VSC, and CEL's but turned out they were from my dumb ___ not tightening down the gas cap all the way. At least that's what I thought because I haven't gotten one in months. I don't know I'll keep an eye on it and if something happens I'll post an update.

BlueJDMBoxV2

50/50 coolant mix dose not start to boil over till you hit 202f. a scangauge would help you keep an eye on your coolant temp. and also lets you keep an eye on almost every thing your motor/car is doing and scans for codes.

stew32

Just a couple of guesses...

Does the xb have a coolant level sensor in the reservoir? If it does, the red overheat light might also be used to indicate low level or bad level sensor. I don't see any reference in the owner's manual for anything other than overheating though.

If the coolant was changed, could be air trapped in the system causing an incorrect sensor reading?

You could check the connection to the sensor and see if that's loose or corroded.

Like BlueJDMBoxV2 said, if you had a scangauge, you could see the temperature the sensor is reading. It's a cheap investment, given the xb's lack of gauges and the ability to display and clear codes.

LeroyJMC

I don't have any other suggestions, but I can deffinitively say that it's not overheating in the first three seconds of startup. You can mark that off the list. A bad sensor can do all kinds of weird things, but don't worry about damage due to overheating in the first three seconds.

365Motorwerks

Good one, don't know if it does but other cars do it..check coolant level would be a great start!

Reactor

xB doesn't have a coolant level sensor.
The blue light will stay on untill the coolant temp reaches 138F. The overheating red light is a different LED and should stay on for few seconds after you start the car just to show that it's working. 15 seconds seem a little too long, but that's most likely decided by the microprocessor in the cluster, so it's probably just an issue with the internal timer.
Would be really good to connect a data reader, like the Scangauge to see what's the actual temp that ECM sees during first few seconds after start.