I’ve had my coolant temperature sensor kick offline numerous times and I’ve actually gotten it replaced three times already. The shop I take it to (where it’s under warranty) says it’s a very common issue on 2011 corvettes. I can’t find any information on it here in the forums though … I’ll usually drive for 5 minutes and then it will say “Service Electrical System” and “A/C Off Hot Engine.” It seems to happen more often when the temperature exceeds 110’ here in Arizona sadly. It happens more frequently and sooner over time until I get it replaced. Does anyone know of some aftermarket parts or other solutions? It is OEM sensor and it is heat wrapped. I have no serious modifications and it drives at moderate engine/oil temperatures.

 

First thing is where are you buying your ECT sensors from ??....if Amazon or Ebay that might be your problem...even if OEM from either one it's most like FAKE...what DTC does it show when this happens ??...if the sensor goes "open" you will see -40 degrees but it may not as there is something called "substituted values" where the ECM will plug in a temperature to keep the car running....the ECT sensor is a 2 wire thermistor...if you disconnect it and jump the 2 wires together the ECT will max out....you can try this and wiggle the wires...this may just be a poor connection....if this is common this shop should know how to diagnose it...if your shop is doing this work and you are getting the "Service Electrical System" message they should do a voltage drop check on the charging system...you want to make sure the ECM is receiving full ignition voltage and even though the ECT and IAT use a 5 volt reference those sensors may be affected.

 

If it is a P0016 this may help...a skewed IAT sensor MAY be the cause.



Circuit/System Description

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit.

The ECM uses this high side coolant rationality diagnostic to determine if the input from the ECT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the ignition is OFF. If the calibrated ignition OFF time is met at start-up, the ECM will compare the temperature difference between the ECT and the intake air temperature (IAT), to determine if the temperatures are within an acceptable operating range of each other.

Conditions for Running the DTC

* DTCs P0112, P0113, P0117, P0118, P0502, P0503, P0601, P0603, P062F, P2610 are not set.
* The vehicle has had a minimum ignition OFF time of 10 hours.
* The ignition is ON.
* The start-up IAT is greater than -7°C (+19°F)
* The Fuel Level Sensor parameter is greater than 5 percent.
* This DTC runs once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

* The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 30°C (54°F) greater than the IAT sensor.
OR
* The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 10°C (18°F) greater than the IAT sensor, and the time spent cranking the engine is greater than 10 seconds, when the fuel level is greater than 5 percent.
OR
* With the power-up IAT greater than -7°C (+19°F), the ECM detects a temperature difference at power-up that indicates that the ECT sensor is 20°C (36°F) greater than the IAT sensor. Then the vehicle must be driven for greater than 6 minutes and 40 seconds at greater than 40 km/h (25 mph). If the IAT sensor then decreases greater than 4°C (7°F), an engine block heater was detected and the test is aborted. If the IAT sensor does not decrease, an engine block heater was not detected and DTC P0116 will set.

Action Taken When the DTC Sets

DTC P0116 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0116 is a Type B DTC.

Reference Information
Schematic Reference

Engine Controls Schematics (LS3) (See: Powertrain Management > Electrical > Engine Controls Schematics)Engine Controls Schematics (LS7) (See: Powertrain Management > Electrical > Engine Controls Schematics)Engine Controls Schematics (LS9) (See: Powertrain Management > Electrical > Engine Controls Schematics)
Connector End View Reference

Component Connector End Views (See: Vehicle > Connector Views > Connector End Views By Name)
Electrical Information Reference

* Circuit Testing (See: Vehicle > Component Tests and General Diagnostics > Circuit Testing)
* Connector Repairs (See: Vehicle > Component Tests and General Diagnostics > Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Vehicle > Component Tests and General Diagnostics > Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Vehicle > Component Tests and General Diagnostics > Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (See: Vehicle > Programming and Relearning) for scan tool information

Circuit/System Verification

1. If the ignition has been OFF for 8 hours or more, the ECT and the IAT, should be within 6°C (11°F) of each other and also the ambient temperature. Turn ON the ignition, with the engine OFF, and use a scan tool to observe the IAT and the ECT sensor parameters. Compare those sensor parameters to each other and also to the ambient temperature. A slight to moderate resistance in the IAT signal or low reference circuit, can widen the spread between the two sensors and cause this DTC to set.
2. An IAT sensor that is skewed lower at various ambient temperatures, due to more resistance than is normal, can widen the spread between the two sensors and cause this DTC to set. Measure and record the resistance of the IAT sensor at various ambient temperatures, and then compare those measurements to the Temperature vs Resistance Table. Refer to Temperature Versus Resistance (See: Computers and Control Systems > Electrical > Temperature Versus Resistance).
3. Inspect the ECT sensor terminals for corrosion, and for engine coolant leaking through the sensor.

Warning

Under pressure, the temperature of the solution in the radiator can be considerably higher, without boiling. Removing the radiator cap while the engine is hot (pressure is high), will cause the solution to boil instantaneously, with explosive force. The solution will spew out over the engine, fenders, and the person removing the cap. Serious bodily injury may result. Flammable antifreeze, such as alcohol, is not recommended for use at any time. Flammable antifreeze could cause a serious fire.

4. Turn OFF the ignition.
5. Inspect the cooling system surge tank for the proper engine coolant level. Refer to Cooling System Leak Testing (Powertrain) (See: Cooling System > Component Tests and General Diagnostics > Cooling System Leak Testing (Powertrain))Cooling System Leak Testing (Charge Air Cooling) (See: Cooling System > Component Tests and General Diagnostics > Cooling System Leak Testing (Charge Air Cooling)) and Cooling System Draining and Filling (Static Fill) (See: Cooling System > Procedures > Cooling System Draining and Filling (Static Fill))Cooling System Draining and Filling (GE 47716) (See: Cooling System > Procedures > Cooling System Draining and Filling (GE 47716)).

Circuit/System Testing

Note: All electrical components and accessories must be turned OFF and allowed to power down.

1. Ignition OFF, disconnect the ECT harness connector at the ECT sensor.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit and ground.

♦ If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify the scan tool ECT Sensor parameter is less than -39°C (-38°F).

♦ If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Install a 3A fused jumper wire between the signal circuit and the low reference circuit. Verify the scan tool ECT Sensor parameter is greater than 149°C (300°F).

♦ If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the ECT sensor.

Component Testing

Measure and record the resistance of the ECT sensor at various ambient temperatures, then compare those measurements to the Temperature vs Resistance Table. Refer to Temperature Versus Resistance (See: Computers and Control Systems > Electrical > Temperature Versus Resistance).

 

do you have OEM heads?

 

That is an incredible amount of information. To be honest though, I live in an apartment and it’s not practical to work on my car myself. I’d wake up 45 people and be sweating my butt off just to get a jack out to the parking lot. (It’s also 115’ degrees outside in Arizona right now). I have been wondering if there is someone else out there who has had the same common issue and found a work around and/or special part. This shop I currently go to has worked miracles for me in the past. … I’m having trouble trying a new shop that might ask for 1000’s of dollars for a relatively small issue. Believe me, I also have a Ford and $13,000 left on a personal loan that I solely used for car repairs. So, I really want to get some research done ahead of time before I recklessly throw money around. Hahaha.

As far as doing something myself with all of that information you’ve provided, could you recommend the minimum tools I’d need to get started on the issue myself? (I actually sold all my tools a few years ago to make rent ironically.)

 

@double06 Yes I do have OEM heads. But it does have a custom exhaust and dummy cats … possibly. (I’m currently using “señor emission” when registration renewal comes around just to be safe.) It is tuned from Dyno Comp too.

 

You would at least need a factory level or equivalent aftermarket scan tool and I wouldn't bother with one of those cheap code readers...you can get a good scan tool these days for less than $500.00...any shop should be able to look at the ECT and IAT sensors and see if something is off if you just want to take in in for repairs...all that info I provided was just Service Info for a P0016...any shop should have this info.

 

The only reason I mention this is sometimes on aftermarket heads the deck is so thick the place where the sensor goes in the sensor bottoms out and squishes/breaks the sensor. You have OEM heads so not a problem.

 

@billyb236 My car is an 11 and has a similar issue, however my car does it when its cold out (under 60*), and I start the car and immediately start driving. The coolant temp will read higher than normal (200-216) while on the highway, whereas normally its 187-195. Funny thing is the oil temps do not rise, which they would if the car was actually that warm, so I know the coolant temp is off. I haven't replaced anything yet on mine, I found that if I let the car idle for a minute or two it won't happen. The car is due for a coolant flush, so I will likely have the coolant temp sensor replaced with an OEM one and see if it still does it.

 

@slowtealz28 I have been to a shop a total of 7 times now for this issue, but I have finally isolated the issue to the gauge cluster today. I will be back on Monday to have it removed and inspected. Basically, this issue leaves no codes or really any trace it was present which is why it’s so hard to pin down. Several theories such as bad wiring, exhaust position, ground wiring, or software glitch were all incorrect.

The sensor has always read correct and was not required to be replaced. The problem lies in the gauge cluster which relays information to the PCM. (Idiotic arrangement). This specific information was not relayed properly through the gauge cluster. Simple as that. The scanner/monitor that the shop used was able to read the correct temperature from the coolant sensor, verify correct analog operation of all of the needles, and see that the system itself was not detecting any problem.

The reason why it may happen when it’s really hot (or cold) out is that the motherboard in the gauge cluster is likely warping and/or not providing power to a certain portion of itself. The shop related it to a smartphone overheating and acting up (before it locks you out). Luckily for me, there is a nearby shop that repairs GM gauge clusters and motherboards. That is where I’m eventually headed Monday if all goes according to plan.

I would highly recommend anyone who is experiencing this issue to focus on the gauge cluster.

 

I’m curious to see how that works out for you. I know my HVAC sometimes will freeze due to the shitty cold soldering I just figured I’d wait to have it redone when I put a shifter in the car.