Hmm, I just noticed after getting some gas tonight, on the Fuel Cap. It says something like "Please make sure you hear 3 clicks when you tighten the fuel cap or CHECK ENGINE light will come on".

Has anyone noticed this?? I guess maybe thats why my check engine light turns on last time without any reason.
How strange?

 

All gas caps (at least all Hondas with the plastic screw on gas cap) must be turned 3 clicks or more...otherwise you may get a check engine light. The fuel cap was designed to be continously "clicked". You can sit there and turn it all day beyond the 3 clicks and (theoretically) it will not break.

 

Yes, there's a chance the check engine light will come on if the cap is loose. However, it a takes a couple of trips before the ECU will complain. Also, if you get the check engine light and you think it's cause of the cap, just tighten it and the check engine light should go away in 3+ trips. If it stays, there could be something else wrong. It's a good idea to find out what the check engine light is complaining about whenever it comes on, so you know for sure.

[QUOTE]Originally posted by bayarea408
[B]Hmm, I just noticed after getting some gas tonight, on the Fuel Cap.

 

2,000+ posts and you are asking this....tisk...tisk:

Prior to 1996 cars used what is known as OBD-I (On Board Diagnostics Revision 1). After 1996 (i.e. all S2000's) OBD-II is utilized. OBD-II has logic codes which now interigate two new systems ("EVAP" and "ORVR"). OBD-I doesn't check for leaks from the vehicles fuel storage and vapor recovery systems. It monitors purge valve operation but doesn't check it for leaks in the fuel lines, gas cap, vapor recovery lines, etc.

OBD-II EVAP systems still check the purge flow, but add a pressure or vacuum test to check the vapor storage system for leaks. Originally the system was designed to test for leaks as small as .040". The S2000 checks for leaks to .020"!!. In addition to sealed gas caps (hence three clicks) and the purge valve, the system adds new plumbing, control valves, and pressure sensors that allow the ECXU to check for leaks. Another big source of hydrocarbon emissions (HC) is the fuel vapor that escapes during refueling. The On-Board Vapor Recovery (ORVR) is a passive system used that reduces the amount of fuel vapor pushed up the neck to the atmosphere during refueling. ORVR uses a mofified fill neck to preclude fuel vapor from escasping to the atmosphere during fueling.

Utah

 

I forgot to put the cap back on once and drove for a mile before I remembered (i know, I know <--twack!!) I didnt notice any light....Not saying it didnt turn on, just saying I didnt notice it.

 

I can confirm that the engine light will come on but not immediately, if the fuel cap is insufficiently screwed back.
I had to take it to the garage to reset, more anxiety than neccessity, and they charged me labour for resetting. Maybe someone would like to loosen the cap as an experiment, and drive until the check light comes on, then tighten it up and monitor how long it takes to reset?

 

I have done enough experiments with the gas cap and EVAP system on my prelude because I was trying to diagnose a problem. The light will definitely come on if you leave the cap off or it's really loose. As for when it will come one, it may come on right away or after 3/4 trips, but it WILL come on and if it does not there's something to worry about. The same is the case with the light going away, it may take it 4 or more trips to go away but it goes away. There is no consistency to when the light comes on/goes off because the way the EVAP tests are done requires a very specific set of variables (temperature, octane, etc, etc.).

Hope this helps.

 

Cars are commonly taken to the shop when this is the only problem. You should check this first and replace your gas cap every few years.

I think the clicks thing is about every car these days. Crown Vics and Lincoln's I think have some kind of arthritis-easy cap. Otherwise, the click caps are very common.

 

Sorry to bring this thread back from the dead.

I just got this CEL today on my '01. I think it might be the gas cap 3 clicks thing. I filled half a tank on Friday morning before leaving for work. Drove to work and back home (two trips total of 20 miles). Didn't use the car on the weekend.

This morning (Monday) the light came on about 1/2 mile from my house.
Stopped the car and opened the gas cap, closed it with 3+ clicks, light is still on.

How many more trips does it really take for the CEL to go off? Can I just make 5 short trips to the grocery store? or is there a distance it has to travel to get that light off?

Thanks

 

Canucks2000, you have to pull the code, otherwise, we don't know if the evap system is really your problem.