Po117 dtc
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,595
Likes: 4,055
From: Cape Coral, Florida
Whenever a circuit “low” DTC is seen it as in your P0117 it can be a wiring issue or a bad (shorted) sensor…there is a 5 volt reference on one of the 2 ECT wires… the sensor pulls that 5 volt reference to ground and that is how the ECM interprets the coolant temp…the ECM sees a voltage and not an actual temperature…it’s too stupid !!…if you take the 2 ECT wires and short them together the ECT will max out to around 280 degrees…if you remove the connector you will see the temp go to -30 or -40 or so…can’t remember the number…the 5 volt reference is either shorted to ground or you have a bad sensor…a thermistor circuit is the only circuit that you can short together and not cause any damage to the ECM…an actual overheat will NOT cause this DTC to set…if you were a little closer I’d say bring your car by…I’d be happy to diagnose it for you.
Last edited by C5 Diag; Oct 25, 2022 at 09:37 AM.
Thread Starter
Drifting
Joined: Apr 2000
Posts: 1,442
Likes: 209
From: Lake Mary Florida
Whenever a circuit “low” DTC is seen it as in your P0117 it can be a wiring issue or a bad (shorted) sensor…there is a 5 volt reference on one of the 2 ECT wires… the sensor pulls that 5 volt reference to ground and that is how the ECM interprets the coolant temp…the ECM sees a voltage and not an actual temperature…it’s too stupid !!…if you take the 2 ECT wires and short them together the ECT will max out to around 280 degrees…if you remove the connector you will see the temp go to -30 or -40 or so…can’t remember the number…the 5 volt reference is either shorted to ground or you have a bad sensor…a thermistor circuit is the only circuit that you can short together and not cause any damage to the ECM…an actual overheat will NOT cause this DTC to set…if you were a little closer I’d say bring your car by…I’d be happy to diagnose it for you.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,595
Likes: 4,055
From: Cape Coral, Florida
If you had a circuit “high” DTC instead of low in which case the coolant temp would read low may cause the fans NOT to run…did your temp gauge actually max out ??…what temp did you see and did the coolant actually boil over if the temp was excessive ??…the fans use a few inputs being the ECT sensor, vehicle speed and AC Pressure sensor….normally with the AC on when I start my C5 the fans will turn on…do you see that on your C6 ??…and FYI any time a “circuit” DTC is seen it’s normally an electrical issue.
Thread Starter
Drifting
Joined: Apr 2000
Posts: 1,442
Likes: 209
From: Lake Mary Florida
Temp gage does its normal sweep at cold start. Analog gage and DIC readout are displaying correct temps. I am led to believe the PO117 sensor is separate from the gage sensors.
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