CHECK ENGINE LIGHT WHEN HOT!

[rooster87]

my check engine light's been turning on on me on hot days. i drive it at night and runs ok and the CEL doesn't turn on. when i drive it during the day when it's hot the CEL turns on. today it's 113 outside and i was driving for a bit. not even too far. turned it off and when i tried to turn it on again it struggled. it's a '93 xj with 'bout 93G miles. manual trans. anybody?

[riverfever]

What is the code?

[rooster87]

gives me coolant temp. sensor and o2. but i changed those already when i first bought the car. (2 months). that's according to the haynes manual though. not sure what the numbers are though. i'll check it out.

[Fish'nCarz]

Did you make sure your coolant was full?

[rooster87]

oh yeah of course. got a new radiator as well.

[rooster87]

What is the code? gave me 12, 22, 21, and 55. could the computer need to be cleared from the memory? i tried by disconnecting the battery for about 15 min.

[Blaine B.]

From my research:

Code 12 = Battery or computer recently disconnected

Code 22 = Coolant sensor signal out of range - May have been disconnected to set timing

Code 21 = Oxygen sensor signal doesn't change (stays at 4.3-4.5V). Probably bad oxygen sensor

Code 55 = End of list.

Let us know what codes you get after disconnecting the battery. Hopefully you'll only get a 12 and 55! Good luck.

[rooster87]

damn...yesterday i changed the thermostat (it was BAD!) and the engine temp switch. both looked pretty bad...but light still went on. got the same codes. the o2 sensor i also replaced not long ago along with the coolant temp. sensor. same freakin codes...oh yeah also it doesn't idle to steady when i turn in on in the morning. rpm starts ok, goes real low then kinda high then goes steady. that's every morning.

[rooster87]

now the light's just on all the time! could the computer be giving a false code? engine doesn't idle very good either. takes a few seconds to go down. think im just gonna take it to get a diagnostic...