well yesterday when i was driving the check engine went back on (i had it on when off-roading driving in 1.5 ft waters and it went out for 1000miles after i disconnected the battery over night). it stayed on for about 20 miles or so. then it turned off yesterday night time. i went to pick up the u-haul dolly and it came back on.

any ideas on why a code would pull up and then clear itself, then go back on? i am thinking its a sensor that is been dirtied/coverd and sometimes it manages to get cleaned off to turn off the code. i'm thinking its a sensor and hopefully something cheap.

what do you guys think of something that might just go on then go off. my dad's bring over the snap on scan tool to check out the code tonight before i make the 750 mile trip pulling a BBF mustang.

like i said, i jst picked up the car dolly and the bronco is asking to pull the mustang and she can't wait.

 

Mine was doing that when my FPR went out. I could drive for about 10-20 minutes before the light would come on everyday. Do you have any black smoke or smell like gas?

 

dad pulled the code and it came out to be "po402, it said "excessive egr detected".

dad says i need to clean up the egr valve because the valve is stuck open? if i can't clean it, i hope i can just replace it for cheap.

i hope it doesn't effect tow/power and mileage.

 

figure around $80 bucks for the egr. there is also a sensor on the top that could be bad causing it to think there is a problem with the egr.

 

It could also be misfiring on occassions this would through a code and then reset, get anything dirty when fourwheeling?

 

Look closely at the egr tube coming up from the exhaust manifold to the egr valve. I had a simular problem with my 93. I got an egr code, went and bought the valve and sensor. When i took the old egr valve off, the tube was broken in half. So i bought a new tube from a salvage yard, and it works fine now, No check engine light. hope this helps.

 

yes i did prolly get something wet and dirty while offroading because i really hit the mud hard and water.

as in right now the code has been off for quite sometime. i'm going to see if it comes on again, and check out those things like you said.