What causes the check engine light to come on?
 

My sister has a 94 civic ex automatic and ever since she had it,its always had the check engine light on.The engine spits real bad sometimes so I think that probably has something to do with it.What kind of things should I check that can cause the check engine light to come on?

Re: What causes the check engine light to come on? (fryman)
 

at the top of this forum is a thread all about cel's (Check Engine Lights)

lol gotta look around man!

THE NEW CEL THREAD (HOW-TO & CODES)
https://honda-tech.com/zerothread/1901557

Re: What causes the check engine light to come on? (fryman)
 

why don't you just go get the cel checked?

Re: What causes the check engine light to come on? (ltrkstr2k)
 

A cel checker?Where do you buy one of those?

Re: What causes the check engine light to come on? (fryman)
 

Damn dawg, go to checker, auto zone, oreilly, napa, carquest, bumper to bumper, any auto parts store will prolly have what is reffered to as an OBD Reader for a honda. For a 94 you'll need an OBD1 reader, and more than likely they'll just test it for you in the parking lot for free.

I'm gonna bet on the O2 sensor...

Re: What causes the check engine light to come on? (eg6imola)
 

Oh.Well I just did what Monkey Magic said and the check engine light turned on 4 long times and 1 short time so I guess thats 41 and then turned on 2 long times and 1 short time so I guess thats 21.According to the cel list that means its the Vtec spool solenoid valve and the Primary oxygen sensor heater.Anyone know where the Primary oxygen sensor heater is located?

Re: What causes the check engine light to come on? (eg6imola)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eg6imola &raquo;</TD></TR><TR><TD CLASS="quote">Damn dawg, go to checker, auto zone, oreilly, napa, carquest, bumper to bumper, any auto parts store will prolly have what is reffered to as an OBD Reader for a honda. For a 94 you'll need an OBD1 reader, and more than likely they'll just test it for you in the parking lot for free.

I'm gonna bet on the O2 sensor...</TD></TR></TABLE>
The OP's sister's car is too old to be checked for free.

Parts stores will check OBDII cars ('96 and up and very few '94 and '95 models - this model not included) for free.

OBDII cars all use the same plug, etc.

OBDI cars use many different plugs. So you'd have to purchase the scanner plus many different adapters that fit different makes and models. It's very expensive and so no one does this for free.

Usually they won't even have the right plug in stock in the store, much less out for store use. Our store usually keeps a couple GM and Ford type adapters, but that's all. We don't perform scans on these cars. I can't remember the last time anyone purchased one either though.

Getting your car scanned at a shop will probably cost about $90. Read the thread that MonkeyMagic linked.

Guessing on the problem will probably cost a lot more than getting it scanned and just fix the problem that shows up.

Re: What causes the check engine light to come on? (fryman)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fryman &raquo;</TD></TR><TR><TD CLASS="quote">Oh.Well I just did what Monkey Magic said and the check engine light turned on 4 long times and 1 short time so I guess thats 41 and then turned on 2 long times and 1 short time so I guess thats 21.According to the cel list that means its the Vtec spool solenoid valve and the Primary oxygen sensor heater.Anyone know where the Primary oxygen sensor heater is located?</TD></TR></TABLE>
It's on the exhaust manifold. Pop the hood and it should be right up front.

Re: What causes the check engine light to come on? (NOFX)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NOFX &raquo;</TD></TR><TR><TD CLASS="quote">
The OP's sister's car is too old to be checked for free.

Parts stores will check OBDII cars ('96 and up and very few '94 and '95 models - this model not included) for free.

</TD></TR></TABLE>

You must have different parts stores. Buddies got a pile of a civic with a mini me he peiced together with all kinds of used parts, and he's in bout once a week checkin cels for free.

Re: What causes the check engine light to come on? (NOFX)
 

Ok so its the oxygen sensor.I wasn't sure what a Primary oxygen sensor heater was because I never heard that term before.I'll check it out.A faulty oxygen sensor could cause the car to spit?

Re: What causes the check engine light to come on? (eg6imola)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eg6imola &raquo;</TD></TR><TR><TD CLASS="quote">You must have different parts stores. Buddies got a pile of a civic with a mini me he peiced together with all kinds of used parts, and he's in bout once a week checkin cels for free.</TD></TR></TABLE>
I work at Autozone here. Two of my managers used to work for Shucks (aka Checkers or Kragen). I used to work for Advance Auto Parts on the east coast too. We also have NAPA and CarQuest here. None of them offer OBDI scanning.

None of those stores had OBDI scanners in stock for scanning in the parking lot. Only OBDII.

There are just too many different plugs.

We have scanned ONE car that was OBDI at my current store. My manager has a collection of Pontiacs and brought his scanner and adapter in to let the guy get his car checked.

So either your friend happens to have someone working at that store that has the correct adapter or he's checking it through the two pin.

Re: What causes the check engine light to come on? (NOFX)
 

Just so you all know...I fixed the Vtec spool solenoid cel and Primary oxygen sensor heater cel.The Vtec solenoid was disconnected so I reconnected it and I replaced the O2 censor so now the check engine light is finally off!Thanks everyone https://honda-tech.com/forums/images/smilies/emthup.gif