Turn off the check engine light

We have a 2003 Lincoln LS that overheated and my husband changed out the thermostat but he doesn?t know how to turn off the check engine light. Can anyone how us how turn it off?

It is best to just wait for the condition that caused the light to come on to clear. If you’ve fixed the problem, then the light will go off after a driving cycle or three.
However, the light isn’t on just for an overheat. If it were, it would have gone off when you restarted the car after it cooled down.

Take the car to one of the auto stores that will scan the OBDII codes for free and see what it is that it is really complaining about. The scanner can also be used to clear the codes and turn the light off, but if you don’t fix the problem it will just come back on after you drive a while.

The light can also be turned off by disconnecting the battery and reconnecting it, but you don’t want to do that. It’s a lot of hassle for no good reason.

If you can’t find a store that does free scans, you can buy a simple scan tool for $50 or less. The LS is a great car, but you will need the scanner.

Have you considered the possibility that changing the thermostat did not fix the problem? Before you do anything else, you should find out what the actual code is. It will be in the format [P1234] It is not saing the thermostat is bad, it is saying ??? We we don’t know until we know the code.

Many codes will turn off after a certain number of cycles (start drive stop). Maybe in a few days it will go out.

We don’t know that the code was read, and the right work was done and maybe even you have now determined that the problem was fixed. But we see a lot of people who make assumptions about a CEL and then ignore it when they think it was fixed or it is just a sensor error etc.

The most common reason for a gen II LS to overheat is that the degas bottle gets very tiny cracks in it and it prevents the cooling system from pressurizing. If your degas bottle hasn’t been replaced, then I promise that it needs to be by now. Thermostats on these cars rarely fail, and when they do it is usually in the open position, not closed.
Also, the plastic halves of the thermostat housing are well known for cracking too, as are the plastic sections of the radiator hoses.
Lastly, it is very important to follow the factory bleeding procedure (to the letter) after doing any work on the cooling system.

The car has done this before. The dealership replaced the bottle in 2007, it overheated again and the dealership replaced the water pump hose that burst. My husband replaced the pressure cap because the bottle and hose had burst. The dealership suggested we might want to replace the thermostat for $200. My husband said he would replace it. When he took the thermostat housing apart he found the tabs that hold the thermostat in position were broken and the thermostat was hanging closed intermittingly. In short the cause of all the problems. He had to replace the housing, the plastic part behind the housing, and thermostat. It?s worked for 3 years. When he replaced the thermostat this time he found the old thermostat?s opening mechanism was sticking. The temperature on the car is now running normal.

Yesterday we took it to Auto Zone and they checked for the code it is failing code p1229. Which has 3 possibilities low engine coolant, drive belt off, or failed cylinder head temperature sensor.

He is going to try the coolant.

The car has 170K and we just bought new tires. We do regular mainteance. I’d like to replace whatever parts noramlly go out so I’m not stuck on the side of road. We would like to keep this car at least another year. What is your opinion?

Thnaks to all that answered you were a big help!

Okay, P1229 is not a valid code for this car.
Are you sure it was P1229, or could it have been P1299?
P1299 is cylinder head over temperature protection active.
The most common cause for this error is failure to properly bleed the cooling system.
It is rare, but sometimes the wire to the head temperature sensor does gets damaged and shorted to the engine somewhere. I would check for that.
It is possible that the sensor has failed, but that is very rare. (Usually if they do fail, they fail with a P1289 error.)

Here is the bleed procedure.

  1. Remove the engine fill cap.

  2. Open the heater air bleed.

  3. Add coolant to the degas bottle allowing the system to equalize until no more coolant can be added.

  4. Install the degas bottle cap.

CAUTION: Care must be taken to make sure the accessory drive belt does not become contaminated with engine coolant.

  1. Add as much coolant as possible to the engine fill. The heater air bleed will remain open.

  2. Install the engine fill cap.
    * Install the engine fill cap until contact is made and then tighten an additional 45 degrees (1/8 turn).

  NOTE: The heater air bleed remains open.
  Start the engine and turn the heater to the defrost (90?F) position. 
  1. Close the heater air bleed when a steady stream of coolant escapes during engine idle.

  2. Allow the engine to idle for 5 minutes, add coolant to the degas bottle as needed to maintain the cold fill MAX mark.

  3. Reopen the heater air bleed to release any trapped air and close again.

  4. Maintain engine speed of 2,000 rpm for 3-5 minutes or until hot air comes from the heater.

  5. Return to idle and verify hot air is still coming from the heater.

  6. Set the heater temperature setting to 24?C (75?F) and allow the vehicle to idle for 2 minutes.

  7. Shut the engine off and allow to cool.

  8. After the engine has cooled, add coolant to the degas bottle to bring the level to the cold fill MAX mark.