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Discussion Starter #1
Odd one that I've noticed over the last few days.

2005 9-5 Aero auto. 125k miles.

The engine cooling fans occasionally run for 30 seconds or so after switching off the ignition. Perfectly normal as far as I'm aware. But over the last couple of days they've run on considerably longer. On one occasion 20 minutes or more before I noticed, flicked the ignition on and off and stopped them. They can be either staying on after switching off the engine or starting up themselves after I've walked away. Levels are normal, no leaks.

Any thoughts? Faulty coolant temperature sensor? Relays? About 6 weeks ago I did flush and change the coolant. Maybe I disturbed something?

I should say I don't have easy access to Tech2 so I'm afraid I can't use that but I have hooked up my generic OBD reader and there were no codes.
 

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I was looking this up in WIS just the other day on someone's behalf. They can start after you've shut down with them not running. There's thermic syphoning going on, and the coolant temperature at the sensor can continue to rise. One thing I do recall is that if they do start autonomously like this, the run time is limited to 3.5 minutes. No codes, and Tech 2 wouldn't register anything abnormal.

Doug
 

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Odd one that I've noticed over the last few days.

2005 9-5 Aero auto. 125k miles.

The engine cooling fans occasionally run for 30 seconds or so after switching off the ignition. Perfectly normal as far as I'm aware. But over the last couple of days they've run on considerably longer. On one occasion 20 minutes or more before I noticed, flicked the ignition on and off and stopped them. They can be either staying on after switching off the engine or starting up themselves after I've walked away. Levels are normal, no leaks.

Any thoughts? Faulty coolant temperature sensor? Relays? About 6 weeks ago I did flush and change the coolant. Maybe I disturbed something?

I should say I don't have easy access to Tech2 so I'm afraid I can't use that but I have hooked up my generic OBD reader and there were no codes.
Did you use the same type of coolant that was in there when you did the flush?
 

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Discussion Starter #4
One thing I do recall is that if they do start autonomously like this, the run time is limited to 3.5 minutes. No codes, and Tech 2 wouldn't register anything abnormal.
Came across the 3.5 minutes reference while I was investigating this. Mine ran considerably longer than that! It has been a touch humid for September but nothing to warrant this behaviour.

Did you use the same type of coolant that was in there when you did the flush?
I used the recommended GM stuff (Dex Cool?) to the correct dilution. No idea what was in before because I've only had this 9-5 since April.
 
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