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Can you reset OBD-II check engine light without scan tool?

6.2K views 9 replies 8 participants last post by  Chris340  
#1 ·
My daily driver 2000 Ford Ranger 2.5 check engine light came on today and the first place I looked was the gas cap and sure enough It was loose. (Another reason NJ needs self serve gas) I am 99.9999% sure this is the problem or just a coincidense that the cap was loose. Truck runs fine.

Is there a way to reset the light without a scan tool. I have read that you can disconnect the battery for a while with the headlights on, start and shut off the motor for 25 cycles, etc. Is any of these true?
I refuse to take it to a shop but wanted your opinions before I drop the $100+ on a simple scan tool.

Any help is appreciated.
 
#2 ·
I think most of the parts houses like Autozone, Advance Auto and PepBoys will check codes for free. They might also be able to reset them if it's a BS code. Are you do for inspection any time soon?
 
#4 ·
I'm good till August.

Thanks for the info on the parts houses, Next time I pass one I will stop in. I am just afraid their inexperience or desire to drum up work will make matters worse. Its worth a shot if I can watch them. Thanks

I will try the battery thing first. Thanks
 
#7 ·
If I've been on the highway for an hour or two, shut the engine off and then restart it, I'll get a BS engine check light. Then if I shut it off again and restart it, it's okay...:scratchhe :shrug

I think it has something to do with the single CatCo, O2 sensor and temperature.
 
#8 ·
BurnedB said:
if that all it was it will reset within a couple drive cycles, and the evap monitor will retest and pass within a week or so.
:stupid
Every OBDII system I have seen that turned on the light becouse of a loose gas cap turned it back off once the cap was retightened.

Get it scanned at the local chaine parts store.

marv said:
If I've been on the highway for an hour or two, shut the engine off and then restart it, I'll get a BS engine check light.
Every time it does that it stores a code in the CM, all you need is a piece of wire and 3 minuts to test it and see what code it is. Then you will know.
 
#9 ·
I'm with BurnedB and Gacknar. My book is out in the truck, and I can't remember, but I think it's after so many miles or so many drive cycles if it doesn't throw the code again, it will clear itself. More than likely if the cap was loose, that was your problem. My teacher for the Electronic Engine Controls class said any time a car comes in with a P0440 code, he instantly goes and tightens the gas cap.