Engine Light = Spark Plug Change?

The engine light in my 2002 Wrangler activated Sunday. Went to an Advanced Auto Store for them to scan and it indicated that the sparks need to be replaced.

Is the scanner fairly accurate about automotive problems and does anyone know what is considered a reasonable price for them to be replaced in the jersey/nyc area?

One mechanic was already talking about the possibility of the airfilter needing to be replaced along with it. Don’t know if this is really necessary as well!

How about if you tell us about the odometer mileage and the last time (date and odometer mileage) that you replaced the spark plugs, air filter, fuel filter, coolant, and trans fluid?

I hope that I am wrong, but it sounds like this vehicle may not have had a whole lot of maintenance over its 8 year life span.

You started on the right path, but you have more to do. You need the code, usually a letter and some numbers like P-200. Then you need to find out what that code means. I don’t know if they can specifically point to sparkplugs, but can say something like “cylinder misfire” etc. Go back to the Auto store, have them read the code and then write down the code and google it. I’d bet against the air filter causing the CEL (check engine light), but it may well be time to replace it. Plugs should be fairly cheap unless the Wrangler is a bear to reach the spark plugs. Also, look on line for a Wrangler Enthusiast Group. Often they know your car really well and can help you on problems like this.

As otheres indicated, the codes don;t get to quite that level of detail, however if they do indicate a misfire and you’re still driving on all your original 8 year old components, a tuneup (plugs, filters, etc.) would be the first thing I’d recommend.

What did the scanner say? It gives a code.

If the code is “random misfire”, you might as well START with the plugs…Next the wires, then the coil(s) then the ECM, then the car itself…

First, thanks for your responses. I will check out the Enthusiast Group 1981.911.SC recommended.

Yes, it has had maintenance regularly through its eight years. Supposedly, it did have a tune up in December '09. Were plugs included in it at that time, I honestly don’t know. There was a problem back then were it would shut off after driving like a certain distance and then it would restart after being off for a while. So, they ended up tuning it and when that wasn’t the cause, they thought it was a fuel related problem (possibly fuel filter replacement.) When that didn’t turn out to be the cause as well, it ended up being sensor related and had been running well since then. Sorry I’m not that schooled in automotive issues/tech. Though, I am learning as problems occur.

The scanner at Advanced showed several codes: P0303, 304, 305, 306 and the guy said sounding confident, that those were codes for plugs that needed replacing. The mileage now is somewhere in the 103,000 range. I believe the sparks were changed within the last four years by the dealers service department. Numerous Jeep dealers in my area (mine included) have gone under within the last eighteen/twenty-four months.

I hope the info I’ve provided helps some.

The “diagnosis” from the guy at Advance is sort of like finding that your TV doesn’t work and having someone say “oh, you just need a new power cord.” Ok, well sometimes that might do it, but what about the other 15 things that might cause the TV to go out?

You’ll want to dig up your receipts and try to verify exactly what was done and when. Misfires can come from bad plugs, bad wires, bad ignition coil or coil pack, distributor problem, fuel delivery problems, and cylinder compression issues, among other things.

Based on what you are saying it doesn’t sound like you can really easily dig into this. So I think you should just find a reputable, local mechanic. Unless it is for warranty or recall service, you never need a dealer.

You mention all of this “tune up” activity in the past, and you have misfires on multiple cylinders. (P030x is a misfire code where the x is the cylinder #). I’d guess that you may have a problem with either the coil pack(s) or distributor - whichever this vehicle has. Or a seriously degraded set of plug wires. But you really want someone competent to just diagnose it.

You aren’t losing coolant are you? Any white smoke out the exhaust? How is the vehicle actually running?

The plugs are probably not the cause of this problem. Seeing as how the misfiring cylinders are the last 3 in the line and each of those last 3 are fired by a separate ignition coil this would mean that all 3 coils would have to be failing at the same time.
Possible, but not likely.

I’d start looking at an injector power supply problem or something like that. I’ll see if I can take a look at a wiring diagram tonight for this vehicle and post back.
(I’m no Jeep expert but they all work on the same principles. Just curious as to how it’s wired up.)