18 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHEngine Bay fan...???
Reported or suspected cause
sensor (located
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Reported cause
the more common issue is the sensor (located on B2 between the intake runners, nearest the upper plenum) will fall from its retention grommet, and be too close to the engine.
Leading evidence: 'sensor (located' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'sensor (located' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check every 10 seconds' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
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1
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Performed · outcome unconfirmed
The switch-on condition of > 78 �C is then checked every 10 seconds.
Run (actuated by fuel pump relay via booster resistance cable)
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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Discussions that contain suggestions
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Suggestion
Ignition ON (for longer than 1sec.) or engine running (actuated by fuel pump relay via booster resistance cable).
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
I was happy it was running considering the temps outside.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion · Original poster
So what ^^this suggests is, the fan was running due to stage 1&2 being met.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
sensor (located
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
the more common issue is the sensor (located on B2 between the intake runners, nearest the upper plenum) will fall from its retention grommet, and be too close to the engine.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
18 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T174436Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
So, I noticed something yesterday that has me baffled. In the 4.5 years I've owned my car I've never heard the engine bay fan run - except when I tested it via Durametric. Well, yesterday (it was close to 100 degrees) after driving the car home from breakfast (about 20 minutes or so - full operating temp left side of 0 in 180) I was going to give it a quick rinse off, rolled the windows up and jumped out. This is when I realized I had left the sunroof popped up, so i just turned the key to accessory... On came the engine bay fan! Needless to say I was somewhat surprised, but given the ambient temp. I was also happy - but a little baffled. Wow...I wonder if I turn the key off, it'll keep running? Nope...turn the key to accessory, the fan runs - turn it off, the fan stops. This seems wrong to me no? I let it run for a few minutes on battery power, but it doesn't seem right. Isn't the fan supposed to run until the engine reaches an acceptable standing temp. regardless of key position (or if the key is even in the ignition?) ? What's going on here? Any ideas on cause? Could it be a bad relay? How should I go about troubleshooting it?
Is it still acting the same way today? Yes, II believe you are correct when the temp. sensor decides it is too hot in engine area it turns the fan on regardless of key position or no key at all.
I think the key needs to be in an on position for the engine bay fan to run. At least that is the behavior I recall from when I troubleshooting on my temp switch.
from the Porsche Service Information Book 2001
1st stage:
Ignition ON (for longer than 1sec.) or engine running (actuated by fuel pump relay via booster resistance cable).
2nd stage:
At coolant temperature of approx. 105 �C or engine compartment temperature of approx. 78 �C (OFF at approx. 60 �C).
After-run phase:
Requirement: Engine compartment temperature with ignition OFF > 25 �C
After-run ON:
For 3 minutes at engine compartment temperature > 78 �C. The switch-on condition of > 78 �C is then checked every 10 seconds.
The after-run phase is active for max. 40 minutes."
Ok ^^^ This is very helpful! My car's a '99, but I can't imagine they changed how the fan works... So what ^^this suggests is, the fan was running due to stage 1&2 being met. But... Not meeting the requirement for "After-run phase or on...
BTW, >25 C (77 F) ? really? That must be a typo... even 78 C (172.4 degrees) is questionable, although much closer to what I would think would be reasonable(right around normal operating temp). It seems to me if this were really the case, than ehgine compartment fan would be running pretty much all the time during the summer months.
My engine compartment fan does run often on my 04 C4S. Obviously i never hear it while moving. But quite frequently i will hear it if i pull into my garage after a long drive and then take a moment before i shut the car down. I think most peoples prob run more often then they realize.
6k miles and i've never heard my rear compartment fan on. before reading your post i thought it might be broken. even this weekend, parking after 30 minute aggressive drive in severe heat and humidity, nada from the rear compartment fan.
^^ This is my experience as well - almost startled to hear it
It is literally the first time I've heard it run without being activated by Durametric. This being said, I'd like it to work as it's supposed to, so I'm just trying to accurately troubleshoot it, and fix if necessary.
I sometimes run with DashCommand showing the intake temp and it's generally not a lot hotter than the ambient temp. Maybe 10-15 F warmer. That's with normal driving, not track. It makes sense that it came on after the car was off and you turned on the key. While driving, the air in the engine bay is constantly moving. When you stop the car, the heat from the engine raises the temp in the bay without the air getting refreshed.
I experienced the same thing this past Sunday after my autocross runs. Air temp was about 99 degrees. I was happy it was running considering the temps outside.
This is a common occurrence with high ambient temps. the more common issue is the sensor (located on B2 between the intake runners, nearest the upper plenum) will fall from its retention grommet, and be too close to the engine. When this happens the sensor sees too much temperature, and triggers this fault. If that's the case, just stick it back in place, and secure it with a zip tie.
This is a source reference. Confirm exact model applicability in the original material.
