Good afternoon folks...My car randomly stalled while I'm driving and I find that after disconnecting the battery for a few minutes and restarting the car, it cranks back up and runs like nothing happened. It did this a few times on the way home and after letting the car sit overnight, the issue went away completely. This also happened last summer when it was really hot outside, but it went away after resetting the ECU. Today my CEL came on and I checked the code and it said it was my O2 sensor but I strangely enough the light went away last night and my gas mileage seems pretty normal and my engine isn't stalling. Any suggestions? I want to just replace the main relay because I think that's the culprit. Any insight would be greatly appreciated. I've got relatively new coils and NGK plugs installed last year so I doubt that's the issue since there aren't any codes being thrown for misfires.

 

What year is your car?

 

It's a 2002 TL-P. I'm leaning towards the main relay since this happened when it was the summer and there's no way an O2 sensor could be bad this entire time and have no effect on engine performance.

 

codes are clues, not a diagnosis in themselves AND can point you in the wrong direction sometimes!

sounds like another case of main relay board solder issue, Known bad problem with a solder area that fails
Ck the diy section for more help

 

Have you ruled out bad ground/battery connections? They can cause the sporadic stalling/shutting off too.

 

Even though it's not a 99, ignition switches are still a pretty common failure. My own experience with main/efi relays is more a start and immediate stall, or cranking no start, especially when a car has been siting in the sun and the interior is about 150 degrees. Fsttyms idea is good as well; especially check the main ground connection at the trans. Honda leaves the last few inches bare to use as a jump start point, and they corrode away to almost nothing. Grounds at the thermostat housing used to be a common problem on hondas, but I can't remember if that applies to ours.

 

2000 counts as a 99, when thinking about the likelihood of a bad ignition switch

grounds- Now that a ziner found the actual connector on end of MAIN battery Neg ground cable was not holding tight to its wire = all grounds are suspect

Even though wires may look ok- a resistance test with multi meter (free harbor freight type) will tell if juice has a clear path or is impeded by corrosion inside the cable itself- wires go bad = welcome to life on Earth
They have been in service over a decade !!

 

My ignition switch is relatively new. But I did pull th main relay circuit board out from the case under the dash and some of the solder points were definately cracked. I went to Acura to get an OEM main relay and I plugged it up and the fuel pump will not cut back on. This is so strange. I'm stumped. I'm not sure about the wiring or if I'm forgetting to reset something...

 

The battery connections seem solid, It's cranking strong but just wont turn over. I dont hear the pump running when I switch the key to the on position. It's really weird.