Can Someone Pleae Help Me

Hello to all
Is there anyone out there that can help me. My Mustang's service enginge soon light came on and the guy at the auto parts store told me I needed a new gas cap??? This is so crazy I have never heard of anything like this he said it gave him a code 401 and that it would be expensive then he came back and told me that all I really need is a new gas cap?? I went and got the cap and the light is still on I was going to disconnect the battery when I get home but my question is how common is the gas cap thing or did I just get played??

Thanks
Shelly

I have a 2003 Mercedes-Benz C230 with a similar problem. Try starting the engine, let it run for 5 seconds, then turn the engine off. Do this 2 more times. This was recommended in my owners manual and it worked. The problem had something to do with emissions sensors being effected by a loose gas cap.

Thanks so much I will be sure to try that, this is just unbeliveable all over a gas cap?

shelly

I believe it has something to do with vapor lock.
Not sure what year you have, but disconnect your battery for 20 minutes with your headlights on. Your computer should be reset after that.

HiFlow 5.0 strikes again!

He's right, it is a vapor problem. These gas cap problems are new to me so please let us know what happens.

wow, ive never heard of that. ill keep that in the back of my head.

Thanks to all of you,However my husband is hunting and left me no tools to get the battery disconnected. So I will try it tonight when he gets home. My mustang is a 2000 and after talking with some of my friends last night they have a jetta and a chevy and they said that if they even put their gas cap on crooked their lite goes on, this just seems odd to me. I just hope is nothing more than that. Once again thanks for the help

HiFlow5 0,

I heard of the lights and 20 min thing before, but I really not think it works as a quick discharge of the circuit. In order for the a circuit to be be complete, you need a pos and a neg, with a load of course. If you take off the neg on the battery, there is no more ground. When you disconnect, you will of course take the battery voltage away, and it will reset the computer, but to really get a quick discharge, you would be better off, sticking a ground rod in the ground, and running a wire to the chassis.

Does this make sense to you guys. I have been in electronic for almost 20 years, and I am still learning. So, if I am wrong, please let me know.

It makes sense to me but it does seem like maybe a lil overkill. Your just trying to make sure any stored energy in the capacitors of the computer are drained.

In my career field, I work on some pretty high voltage pieces of equipment. When we want to make sure the caps are discharged we use a grounding stick. To me the same theory applies to the cars ECU. Just food for thought.

Plus, you do not have to wait 20 min. You just have to ground it out with earth for about a couple of secs, and you are reset. That is the way I do it. :)

In my career field, I work on some pretty high voltage pieces of equipment. When we want to make sure the caps are discharged we use a grounding stick. To me the same theory applies to the cars ECU. Just food for thought.

Plus, you do not have to wait 20 min. You just have to ground it out with earth for about a couple of secs, and you are reset. That is the way I do it. :)

Yea but that 20 minutes is my pop a beer, relax, drink my beer, and hope it works time! Don't take that from me Skyline, let me have those precious 20 minutes!

Yea but that 20 minutes is my pop a beer, relax, drink my beer, and hope it works time! Don't take that from me Skyline, let me have those precious 20 minutes!

GTStang, It's like your reading my mind. Patience is a virtue.

GTStang,

Good point:)

I am running down to the PUB. Good English Beer:)

Yea but that 20 minutes is my pop a beer, relax, drink my beer, and hope it works time! Don't take that from me Skyline, let me have those precious 20 minutes!
Exactly!

The head light thing is just to drain and excess voltage left in any capacitors and such. The 20 minutes is to make sure all power is drained. This is what an ASE certified mechanic has told me in the past. Plus I like the beer thing too!

Ok so here is what the real problem was!!! It was not the gas cap unfortunatley the light came back on I took it to a different location (same company) and had it re-tested it was my EGR valve. After purchasing the valve the guy told me to just take off the old one and clean it out with carb cleaner and return the unused part. hmmmm did it still keeping the part for a few days to make sure it dont come back on but thanks to all for helping me

Shelly

it was my EGR valve.
Shelly
Darn, that was my next guess.