I know I have to replace my thermostat but this

[HJr]

morning, the gauge jumped from the blue to red making in a second and then the Engine Service Soon light came on. Is that thermostat stuck closed when it does that? I'm not getting any heat. Once I shut the car and turn back on it goes back to the blue marking....then drove again and did the same thing jumping to the red marking. The ESS light still on.
2001 530i SP

[Craig in Canada]

Thermostat open/closed doesn't make the heat work or not. The heater core is on the "inside loop" and gets coolant circulation regardless of the position of the stat. You've got something else going on too - air pockets, temp sensor problems? Jumping from normal to red in 1s isn't what would be expected and might be a false reading. You need to get that code read too as it may point you in a good direction.

[JimLev]

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[HJr]

2001 530i SP

[HJr]

with the temp gauge not reaching the middle. Ever since it kept dropping torwards the blue marking
2001 530i SP

[JimLev]

See #3
http://www.realoem.com/bmw/showparts...69&hg=11&fg=15

[Craig in Canada]