Engine Compartment Fan

[nosnow]

I just recently aquired a 99 Boxster from a friend and I'm having an interesting problem with the engine compartment fan. I was told the car always did this but when it was new I didn't remember it doing this.

Issue: Starting from cold the engine compartment fan comes on at high and stays on for ~4-5 minutes. The fan also seems to kick on and off randomly throughout stop and start driving. The weather is not hot and I'm not driving aggressively. No engine faults or warning lights and the engine temp never goes much above 180. If memory serves me correct the fan only came on when very hot and not at start-up.

Thoughts? I was thinking a bad temp sensor but maybe it is something else.

[Tool Pants]

There is an electric smog pump that comes on when the engine is cold, then go off as the engine heats up. Maybe that is what you are hearing. The pump does sound like a fan.

[therock88]

I just recently aquired a 99 Boxster from a friend and I'm having an interesting problem with the engine compartment fan. I was told the car always did this but when it was new I didn't remember it doing this.

Issue: Starting from cold the engine compartment fan comes on at high and stays on for ~4-5 minutes. The fan also seems to kick on and off randomly throughout stop and start driving. The weather is not hot and I'm not driving aggressively. No engine faults or warning lights and the engine temp never goes much above 180. If memory serves me correct the fan only came on when very hot and not at start-up.

Thoughts? I was thinking a bad temp sensor but maybe it is something else.

I am no expert on Boxsters especially...But I think it sounds like a temperature sensor as well. I had a similar issue with my wife's Cayenne and that solved the problem.

Good luck!

DC

[Loren]

I think you are confusing the emissions secondary air pump that comes on and stays on when you start the car. This usually stays on 2 -5 minutes depending on outside air temperature and how long it takes to get the engine up to temperature for proper emissions control.

The cooling purge engine fan only comes on when the temperature in the engine compartment exceeds a set level. This is actually not very often - unless the engine compartment sensor has fallen (or been knocked) out of it's golder and it laying on the engine

[nosnow]

I'll buy the emissions pump.... didn't realize this new of a car would have one of those. I thought the new catalytic converters were so efficient air pumps were a thing of the past.

Thanks

[JFP in PA]

The M96 runds a bit rich at start up, to comply with 50 state emissions standards, it uses a secondary air injection pump for a short period after starting.

[N41EF]

From the answers you got from above, there are two different fans or blowers. YOu may be hearing each of them thinking they are the same. There is an emmissions blower than runs on startup for a few minutes, and an engine compartment fan. My engine fan runs intermitantly in stop and go driving, I usualy only notice it with the top down, but during the commute as I come to a complete stop I hear it start and run maybe 5 seconds then shut off. I assume that it is normal and it is coming on to check temperatures to see if it "needs" to run longer. The emmissions pump runs as noted above.

[ARModen]

If you have a durametrics cable or know someone that does, you can cycle the different fans on and off to figure out which fan you are hearing without the engine runnning.