Engine light continues to come on

2007 subaru forester misfired–engine light came on; brought to dealer. Replaced airfilter and turned light off; two days later misfired again; took back to dealer and they turned light off. Told me to use higher test gas (this is not a turbo forester). A few days later light came on again. After the original misfiring message, the current code is insufficent flow through catalytic onverter. At 44,000 miles is the catalytic converter plugged or defective? How can one be certain that is the problem? The car runs beautifully, except that I can’t use cruise control with the engine light on. I plan to take it back to the dealer again, but am becoming a little frustrated.

You shouldn’t have to use gasoline with higher octane than the owner’s manual recommends. If the manual says regular is OK, then the engine should run on regular. If the manual says premium is “recommended,” then you should probably use premium.

A friend of mine has an '07 Forester and she never uses anything other than regular gas.

I had a misfire in a Subaru that turned out to be a bad spark plug. They figured this out after testing about a dozen other things. If the misfire comes back try a new set of plugs. They’re cheap.

The catalytic converter is another issue, but should be covered under the emissions warranty.

You may want a dealer to perform the services covered under the warranty; but, you DON’T want that Subaru dealer! No. Find a dealer with mechanics, and knowledgeable service managers.
The problem with the catalytic converter isn’t caused by the catalytic converter. It’s caused by faults in the engine and engine management system. Don’t let them b/s you about that.

"Find a dealer with mechanics, and knowledgeable service managers. "

Good Luck…

Any decent shop can run a back-pressure test on the CAT. I would replace the plugs and plug wires, try that, then, on 1/4 tank of gas, try a can of BG formula 44 to clean the injectors. You can reset the CEL yourself by disconnecting the battery for 30 seconds. At 44,000 miles, you can DEMAND the dealer properly repair the car under its emissions warranty…This is not YOUR problem, it’s Subaru’s problem.

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

If you had inefficient flow you’d have low power and difficulty maintaining highway speeds. I suspect you mean that it indicated inefficient operation of the cat converter.

Since the car is this new and running so good I’m betting you have a bad oxygen sensor. The computer monitors the cat converter by comparing the oxygen sensor output before the converter (upstream) and the one after the converter (downstream). A failing sensor can trigger a code that suggests a bad converter, and it can also cause misfiring.

I agree with the others…you need a good shop to look at this.

We have a problem here “insufficent flow” is a phrase linked to the EGR system (P0401). Converter codes relate to Cat. “efficiency” (P0420) for example.

As we usually do I will request the codes by number so we can be sure what we are talking about.

I am concerned with the misfire code being deleted but not diagnoised.

If you want to know what to ask the Dealer did to declare your Cat. dead post back I will tell you.

Are you complaining that the Dealer is not working with you under warranty on this or just trying to understand what’s going on?

You need to make sure that the symptom, “I can’t use cruise control with the check engine light on.” gets transmitted to the mechanic who works on your car. Telling the service advisor assures you of nothing; but, do it anyway. Also, write a note, of the symptoms, for the mechanic and leave it on the seat, and tell somebody that you have done so. The mechanic may get, and may read, your note. Maybe.

Right off the cuff, I’d say the dealer is stabbing in the dark.
However, I’d also like to know if there’s more of the story behind this problem since things that have been done so far are of a dirt cheap or free nature.

Are you taking the car in and complaing about wanting it fixed on the cheap or for free or are you telling them here you go, fix the problem?

If it’s “misfiring” how can it “run beautifully”?

There also needs to be some info provided about exactly what codes are present. Considering the car runs beautifully according to you, it’s unlikely there would be a clogged converter problem.
In the event of a converter problem the cat is covered by the Fed. Emissions Warranty for 80k miles and 8 years but I’m not sold at all on the converter being the problem. Something(s) is missing here.

thanks. Subaru dealer finally diganosed problem. Will replace catalytic converter.

I had this SAME problem with my nissan. Took it to a shop, the guy said it’s not your Cat. Took out a pipe cleaner and cleaned out some residue in the pipe leading from the cat to the sensor. Never saw the check engine light again. I hope this helps, Im not too great at being technical.

I have experiences similar problems with Chryslers that have multiple oxygen sensors throughout the exhaust system - hard to find out which one was sending bad info to turn on the CEL.

I see your latest post, dated 04/07/2009 at 09:29 AM. “The dealer will replace the catalytic converter [under warranty?]”. Well, it’s good the dealer is removing the symptom. The causes have not been removed (If least, you didn’t report such). Until the causes are remedied, the symptoms will come back, and the catalytic converter will plug up, again.

True. Doesn’t remove cause by replacing catalytic converter. However, I suspect the original cause was bad gas. The first code reportings were for misfiring. It was so bad I couldn’t drive the car. I had to use an injector cleaner to get it running. Since then, the code has always refered to lack of flow. I am willing to try their solution since it doesn’t cost me anything. The car is still not fixed since I was informed on Friday that they received the wrong converter from their supplier. Supposedly,the rear converter is the problem I didn’t realize it had two converters.

Thanks for all the great advice. Perhaps a simple cleaning will help.

The original problem was misfiring. “Bad Gas” is an unsubstantiated guess----similar to what the dealer has been doing.
The cause of the problem, misfiring, has not been uncovered (or, maybe, that’s ACCIDENTALLY discovered?). The massive misfiring fed the catalytic converter(s) far more fuel than they could digest, and they self-destructed (immolated?).
Part of the problem of non-diagnosed problems can be laid at Subaru’s corporate door-step. Subaru allows the dealer way too little diagnostic time. To do a diagnostic in Subaru’s allotted time, the mechanic would have to have instantly made the diagnostic (which is impossible), and then, just used the allowed diagnostic time to exactly confirm that diagnostic. Can’t be done.
Call Subaru of America and tell them that your car has NOT been properly repaired (even considering the replacement of the catalytic converter(s)). Insist that it be properly repaired. They may recommend another specific dealer (independent shop?). Or, they may blow smoke. You don’t smoke that stuff, do you?
Don’t be afraid to download, and print, these posts and take them to the affected (afflicting?) parties. Unrepaired, this problem WILL cost you a lot of $$; if not today, then tomarrow.