dv3

if my computer has error codes would my check engine light come on?
how do u reset the computer?

nitrous_bob

remove the batt cable for 20 minutes (i think it's 10, but i go longer)

richinwa

You have an OBD II system and if you check engine light is one then there is something wrong. Or you will get stored codes and it will read something like 24-10-11 The first code is a stores code, the 10 is pass and the 11 is no hard fault. SO if you have the 24 in the first position then no the check engine light will no allways come on. When you have a code in the third postion then it should come on.

dv3

my light is not on but ...in wondering if it is worth checking for codes if my light isnt on ...i am having an idle issue but no check engine light

Joel5.0

The EEC in your '92 is NOT an OBD-II system....no 5.0L Mustangs were OBD-II.
There are only specific failure codes that will cause the CEL to turn on, so yes.....you could have failure codes stored and not have the CEL turn on....and yes you should perform the self-tests KOEO(=Key On Engine Off) and KOER(=Key On Engine Running).... http://www.troublecodes.net/Ford/

Negative ghost rider.....EEC-IV = OBD-I system.
KOEO codes are categorized as On Demand Codes - 10(separator) - Continuous Memory Codes, in the example you posted would be......
24 = Intake Air Temperature/Air Charge Temperature Sensor Out Of Self Test Range. 0.3 to 3.7 volts(O)=On Demand code
10 = Separator
11 = System Pass (M)=Memory Code

gspfunk

Listen to Joel...he knows his stuff.

Run the KOER/KOEO tests to see what codes are stored before you reset the computer.

namor1235

yes if your having a problem that is not visible 1st step to a diagnose is check the DTC codes. it doesnt matter if the light is on or off u can get a code for the light not being on, orif theresno light at allcheck itclose ignition and reopen it spot the light and u'll know if its working or not. like i said just because the computer doesnt throw the light it doesnt mean theres no code.

the computers are smart they will try to fix the problem before they say f it and throw the light.