Any HELP- "Check Engine" Light, 96 C4S
08-21-2008, 02:21 AM
#1
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Any HELP- "Check Engine" Light, 96 C4S
Thank you for your time.
Everything works fine.
Some days the "Check Engine" light comes about 30-40 minutes into my drive.
The same day in the afternoon, it will come on with startup and stay on.
Maybe the next morning it will be on, maybe not.
Car has a new top end with only 10k miles on it, so it shouldnt be a carbon issue.
Only mod is airbox.
Anyone know the deal on this infamous annoyance?
Again Thanks.
Everything works fine.
Some days the "Check Engine" light comes about 30-40 minutes into my drive.
The same day in the afternoon, it will come on with startup and stay on.
Maybe the next morning it will be on, maybe not.
Car has a new top end with only 10k miles on it, so it shouldnt be a carbon issue.
Only mod is airbox.
Anyone know the deal on this infamous annoyance?
Again Thanks.
08-21-2008, 02:31 AM
#2
RL Technical Advisor
There are SOOO many things that can trigger the Check Engine light thats its virtually impossible to speculate about the cause. 
You really need to plug a scan tool (Hammer, PST-2, or generic OBD-II) to see whats going on. Anything else is simply WAG's,..
You really need to plug a scan tool (Hammer, PST-2, or generic OBD-II) to see whats going on. Anything else is simply WAG's,..
08-21-2008, 11:32 AM
#3
Three Wheelin'
Go to Autozone and they'll attach an OBD-ii scantool and tell you
i) the code(s) that are triggering the CEL and
ii) PENDING codes that may trigger a CEL in the future
The fact that the CEL "goes out" tells me that - whatever triggered the 'error condition(s)' to begin with - has, over time, cleared itself. OBD-ii does that -- it will nullify the error if, over repeated cycles, the same condition that triggered the original error DOESN'T crop up (again). Thus, your 'problem' may very well be transient. Could be something as simple as a loose or 'iffy' connection somewhere (electrical or vacuum) or 'dirt' somewhere that is periodically messing up a sensor.
Anyways, enuf speculation ...get thee to Autozone !!!
Gerry
i) the code(s) that are triggering the CEL and
ii) PENDING codes that may trigger a CEL in the future
The fact that the CEL "goes out" tells me that - whatever triggered the 'error condition(s)' to begin with - has, over time, cleared itself. OBD-ii does that -- it will nullify the error if, over repeated cycles, the same condition that triggered the original error DOESN'T crop up (again). Thus, your 'problem' may very well be transient. Could be something as simple as a loose or 'iffy' connection somewhere (electrical or vacuum) or 'dirt' somewhere that is periodically messing up a sensor.
Anyways, enuf speculation ...get thee to Autozone !!!
Gerry
08-21-2008, 12:31 PM
#4
Drifting
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...or Harbor Freight. I got his one on sale for $29.99:
http://www.harborfreight.com/cpi/cta...emnumber=94168
http://www.harborfreight.com/cpi/cta...emnumber=94168
08-21-2008, 06:00 PM
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08-22-2008, 11:12 AM
#7
Rennlist
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The standard cause of the fault for P0300 is Faulty spark plugs or wires
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer
But when a 993 throws this fault code it is generally related to electrical related issue, like an alternator belt, battery, ground etc.
But if your CEL comes on an off, it is probably not a misfire CEL.
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer
But when a 993 throws this fault code it is generally related to electrical related issue, like an alternator belt, battery, ground etc.
But if your CEL comes on an off, it is probably not a misfire CEL.