Help! Error codes 14,45,42

[joe j]

I have a 1991 Corvette that has 19K miles. It has an intermittent problem (service engine soon) showing error codes 14,45, and 42.
After the car is shut off for a while, I re-start and it runs perfect. The coolant sensor has been replaced, new wires, cap plugs, etc.

Any ideas?

Joe j

 

[Hib Halverson]

DTC14 is a fault in the coolant temperature sensor or the sensor wiring
DTC42 is a fault with the electronic spark control
DTC45 is a fault which causes the engine to run rich.

Have you read the Factory Service Manual and performed the diagnostic procedures listed in the manual for those codes?

 

[John Robinson]

Could you give us some history on the car such as.

How long have you had the car?

How much gas was in the tank when you got the car?

Or are you the original owner?

How far have you driven the car since you got it?


Have you put new gas in it since you got it?

How has it been stored to have such low mileage?

All these questions will help to determine if you are suffering through the pains of bringing a low mileage car back to life.

 

[vette079]

Wich coolant sensor did you replace?
The one in the front of the TB is the one that sets a code.

 

[toptechx6]

DTC14 is a fault in the coolant temperature sensor or the sensor wiring
DTC42 is a fault with the electronic spark control
DTC45 is a fault which causes the engine to run rich.

Have you read the Factory Service Manual and performed the diagnostic procedures listed in the manual for those codes?

Definitely agree with Hib, follow the step by step troubleshooting procedures in the FSM for best results. Best practice when there are multiple codes in memory is to troubleshoot the lowest numbered code first, once it is repaired clear the remaining codes from the ECM using a scan tool or by disconnecting the negative battery cable then road test to see if any DTC's return. If they do return, again follow the guidelines above until all are resolved.

 

[joe j]

Wich coolant sensor did you replace?
The one in the front of the TB is the one that sets a code.

That's the one I replaced

 

[vette079]

That's the one I replaced

After deleting the codes, and installing a new sensor, you still get that code 14?
Check the connector in that case.
You didn´t apply any coating on the threads did you?
You should not use loctite or anything on the thread, or else it won´t ground properly.

 

[joe j]

Could you give us some history on the car such as.

How long have you had the car?

How much gas was in the tank when you got the car?

Or are you the original owner?

How far have you driven the car since you got it?


Have you put new gas in it since you got it?

How has it been stored to have such low mileage?

All these questions will help to determine if you are suffering through the pains of bringing a low mileage car back to life.

I have owned the car for 4 years, and I am the second owner. I have driven the car 7,700 miles since I purchased it, it only had 11300 at that time.

 

[joe j]

After deleting the codes, and installing a new sensor, you still get that code 14?
Check the connector in that case.
You didn´t apply any coating on the threads did you?
You should not use loctite or anything on the thread, or else it won´t ground properly.

I checked the connector with a meter back to the ECM - checked OK- Nothing on the threads. I think I will do a complete cooling system flush and fill and replace the temp sensor again, and as long as I am in there do a thermostat.

 

[John Robinson]

Ok now we know that the car has been driven and has fresh gas in it. That temperature sensor you replaced has a ground wire that goes to a bundle of ground wires. Trace it back until you find were it is joined by the ground from the several other sensors. It should be a section that has a big blob of electrical tape wound around the wires. Time and moisture will cause that bundle connection to corrode and since the ECM takes all its information from the grounds. Therefor if it is getting a weak signal it will adjust in an effort to get the correct value for that sensor. When it does this it sends a code for the sensor since it does not have any way to determine if the sensor is bad so it simply says look at this system for the problem. With the long cold winter storage time were you live stored cars are a home with building materials for the mice that come in from the outdoors to stay warm. They seem to think electrical wiring is a delicacy.





As for the codes 42 and 45 you need to clean the grounds to the frame. As earlier stated the FSM is the source of what to do to diagnose code problems. If you have a FSM it would tell you to check the grounds on all of the circuits referenced by the code. I am only providing this thumbnail look at what you it would tell you to do just in case you don't have an FSM(Field Service Manual)

 

[joe j]

Ok now we know that the car has been driven and has fresh gas in it. That temperature sensor you replaced has a ground wire that goes to a bundle of ground wires. Trace it back until you find were it is joined by the ground from the several other sensors. It should be a section that has a big blob of electrical tape wound around the wires. Time and moisture will cause that bundle connection to corrode and since the ECM takes all its information from the grounds. Therefor if it is getting a weak signal it will adjust in an effort to get the correct value for that sensor. When it does this it sends a code for the sensor since it does not have any way to determine if the sensor is bad so it simply says look at this system for the problem. With the long cold winter storage time were you live stored cars are a home with building materials for the mice that come in from the outdoors to stay warm. They seem to think electrical wiring is a delicacy.


View attachment 4627


As for the codes 42 and 45 you need to clean the grounds to the frame. As earlier stated the FSM is the source of what to do to diagnose code problems. If you have a FSM it would tell you to check the grounds on all of the circuits referenced by the code. I am only providing this thumbnail look at what you it would tell you to do just in case you don't have an FSM(Field Service Manual)

I can't thank you enough, quite a few ground locations on one of these fiberglass monsters. I think I will take my time and check all. It can't hurt. With some of the ghosts I have with this car it might be the cure. I will keep you posted