V8 Stingray

So guys, took my C4 out of hibernation today here in snowy Ireland for a Cars n Coffee spin and half way along the journey the dreaded Service Engine Light Soon light came on. Stayed on for the 1.5hr journey there, but on the return journey the light didnt come on. Car seems fine, no lack of performance, but there is the hint of a hesitation/miss.



When I got home I checked the OBD codes by jumpering the pins and got a code 14 - "Coolant Sensor circuit low". The coolant temp is fine in the car, so I'm guessing a bad sensor. I also read before that a faulty coolant sensor can have an impact on the running of the car. Where is the location of the sensor on the engine? (I also checked all of the injectors, and they are all running within normal parameters).

I've uploaded a video here of the car running and idling (warm after the run)
While checking for loose connections I came across this sensor on the drivers side (looks like the knock sensor?) the plastic housing on the connector was so brittle it broke off in my hands.

Sensor connection housing brittle - broke off

Knock Sensor?

While I was at it I was checking for vacuum leaks. I noticed this port on the intake plenum (drivers side) - should this be connected to something?



Appreciate any guidance!

cdm747

The sensor shown between the plugs should be your dash temperature sensor. Sensor is located between cylinders 1&3. That is not a vacuum port, it is a post that is supposed to have a support for the throttle cables. Only vacuum ports on an 88 should be the two on the passenger side of the plenum.and the large one under the plenum for the brake booster.

V8 Stingray

Ah perfect.... I wast thinking that was it alright as it wasnt like a normal vacuum port. Another part to order!

V8 Stingray

So I'm guessing there are 2 x coolant sensors - one for the in dash temp display and another relating to the OBD Code 14 sensor error? Where is this one located?

cdm747

Coolant temp sensor for ecu is in front of engine by water pump

65Z01

Indeed Code 14 indicates Coolant Temp. High; the sensor is found just below the TB.

At operating temp. the Yel wire should show a voltage between 1.5-2.0 Vdc. When cold the voltage should be near 5.0 Vdc.

FelixP

I had the same problem and it was the wiring for the CTS. I replaced the sensor and spliced in a new pigtail

cdm747

Sorry, brain fart, was not thinking. Happens when you get old.