Check Engine Light

[exp999]

Accidentially posted in the modified section, meant to ask in the Stock forum.

Looking for help ... I changed the thermostat on 96 Explorer with a Ford replacement and refilled the antifreeze in the overflow tank and the radiator. Drove it around for a mile and all looked fine. The next time I used the explorer, the Check Engine Light came on.

Is the light related to the thermostat change AND how can I check the code without an analyzer?

Any help is appreciated.

 

[00XLS]

The light could be, but you can't check it without a code scanner. Go to autozone and they'll pull the code for free. Also check the coolant and such again.

 

[IZwack]

the engine doesnt really have any way giving specifics on problems other than throwing the 'cheng engine' light.. (unlike the transfer case for example which you can at least count the number of time the light blinks). you really need a code reader. you can get one from like HarborFreight for like $40-$50. its an el cheapo solution but hey it works.

how is the temperature guage? is it in normal ranges? it should be below the half-mark.

 

[ExplorerDMB]

did you "bleed" (get all the air out) of the coolant system after you were done filling it back up.

-Drew

 

[exp999]

Thanks for your advice ... temperature gauge is below half mark much better then before since it hardly moved before. Probably the thermostat was stuck open and no check engine light then.

I bled the air out but can try again this weekend. The coolant level in radiator and overflow tank is good.

Does the check engine light reset after turning car on a number of times?

 

[IZwack]

if the computer doesnt see any problem, then it will not light up the check engine light. however, assuming you havent disconnected the battery, the code will still be stored in memory.

 

[Glacier991]

A check engine light will turn itself off if the code is not constant after a number of starts. (In other words it the fault appeared once then disappeared and stays disappeared) I forget the "drive cycles" as they are called, but I think it's 20 or so. So your answer is yes.

 

[HappyGilmore]

http://fordfuelinjection.com/?p=13

you can run a self test to pull some codes. then you can look up what the codes mean on that website too.

 

[TheJMan]

http://fordfuelinjection.com/?p=13

you can run a self test to pull some codes. then you can look up what the codes mean on that website too.

This would work on the 91-94 Explorers, but since he has a 1996 with OBD-II, this wouldn't work. Need to have a code reader to pull codes on an OBD-II.

 

[exp999]

Recap: Old thermostat must have been stuck open since temp gauge reading was very very low for almost a year. Replaced the thermostat and am sure I bled the air out. Temp now reads normal. Since the change, the Check Engine Light came on.

Stopped by AutoZone this morning and they pulled down 2 codes: P0113 and P0420

P0113 - Intake air temperature sensor circuit high input
P0420 - Catalyst System Efficiency Below Threshold (Bank 1) for the current engine operating conditions.

The codes were erased, should the Check Engine Light disappear after so many recycles or do I still have the problem?

 

[Glacier991]

To answer your last Q first, it takes 40 drive cycles for that to happen. However my guess is you still have the problem. This is a case where a scanner (not code reader) would be invaluable. I'd check the Air Intake sensor and all associated wiring (if the wiring is ok and if it's cheap (never priced one), go ahead and replace it). A scanner would be worth it's weight in gold on this one. If you can get your hands on one DO. Look at the reported value for intake air temp, look at the activity of the downstream 02 sensor (if reported) and look at short and long term fuel trims. You can get a real good idea of what's going on that way.