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Clearing the codes on my Focus

I have a 2002 SVT Focus I bought new, and it now has 91K miles. The unique (and low-hanging) SVT tubular exhaust header got bent, and I had it replaced at a custom exhaust shop, along with the damaged Cat and Oxygen sensors. (The dealer had wanted to replace the catalyitc converter too, which on an SVT is shaped like a pretzel and costs more than a new engine assembly. No kidding. Turns out there was nothing wrong with it.) The car runs much better now, but the guy didn’t have an OBDII scan tool to reset the computer, so my check engine light is still on. (He ususally does hot rods and race cars and such.) According to my repair manual, the engine may still be in get-you-home mode and not running optimally. It there any way to reset the computer without a scan tool? If not, how much might it cost me for my regular repair shop to do it? It cost me a hundred bucks just to have them scan the codes in the first place. On my previous car, a 1995 Neon Sport, you could pull the main fuse under the hood, start the engine, and it would run rough for a few seconds, then everything was back to normal. Of course, on that car you could also turn the key on and off five times and the get the error codes yourself. This is progress I suppose. Any advice is greatly appreciated.


Paragraphs? Your post is hard to read.

The hot rod shop doesn’t have an OBDll scanner? Shame on them.

C’mon, we’re living in the twenty-first century. Cars have computers now. And fuel injection, stuff like that. Every shop needs a scanner.

Try disconnecting the battery for 1 minute or so. Just remove one cable…

A scan tool can be had for less than $100, and it reads codes as well as erases codes. And, it can be used many times. Savings? Bunches!

OBDI systems you could clear codes by disconnecting the battery. On OBDII systems, disconnecting the battery won’t clear codes, and may cause problems with the adaptive memory of the ECU and modules. This is 2009, not 1994.


Well, as luck would have it, my Focus healed itself. The check engine light went out late this afternoon.

Apparently driving around for several days with no wacky readings from the sensors is enough to convince the ECM that everything is fixed, and it switched off the limp-home mode. The occasional stutter is gone, and the old girl runs as strong as ever. Dammit I love running’er up through the six-speed.

Considering the shop charged me $3000 less than the estimate from the dealer…that’s THREE THOUSAND DOLLARS…I’ll forgive them for the scan tool. Maybe I will pick one up one of these days.

Shame on the dealer mechanic who wanted to replace a perfectly good Cat. I recall a mechanic I knew some years back complaining that mechanics today aren’t mechanics, they’re “parts replacers.” That’s really hitting home right about now.

And from now on I won’t forget the paragraph thing, I promise.

For what it’s worth. It wasn’t in “limp home” mode, it was in “open loop” mode, which means the ECU will still use the oxygen sensor to read air/fuel ratios, but will not adjust the fuel delivery like it does in “closed loop” mode. Even in open loop mode you can drive the car normally. It just means the fuel air mixture is going to be a little off, most of time it ends up running a little rich.

My '98 Vic, OBD-2 equipped, (All 1996 and newer are OBD2) clears it’s codes by disconnecting the battery no problem. Dude.

If you’d like to get your hands on an OBD code reader/eraser that does the job for very little money, consider this:

I got one of these from Pep Boys for even less than this ($50), works like a charm.

Wal-Mart has the scanner you need. $97.something. Actron. When you reset the codes, the indicator lights will start flashing and will stop when the drive cycle is completed. You can unplug it at that point or complete the drive cycle first and then unplug it.

The code scanner that Bud2049 shows a link to is a pocket-size unit. I looked at the information on it; but, I didn’t see where it can read vehicle which use the OBDII CAN communications (multiplex) that began in 2003 and all vehicles must use by 2008 (and beyond). Perhaps the packaging shows if it is CAN capable?

Here is the user manual for that scanner, in downloadable pdf:
Anyone who wants most DTC code definitions, CODES FOR ANY CAR OR TRUCK, can go to this pdf and look it up. I Bookmarked it.

Here is the list of ALL vehicles which have the CAN protocal from 2003 to 2008: (Regulars: you should Bookmark this link).