Reading DTC codes without a scan tool (check engine light)

**lbarouf** · 02-21-2015, 01:14 AM

Got the check engine light on?
No fret... no need for an expensive (nor a cheap) ODB-II reader. Our 10k tin cans can read off the display.

Jokes aside, it can become useful

Here's how to read and reset:

Read
* Turn the ignition key to the ON position and wait three seconds. (Do not start the car.)
* Fully depress and release the accelerator pedal five times in less than five seconds.
* Wait exactly seven seconds.
* Fully depress the accelerator pedal for ten seconds until the check engine light flashes.
* Release the accelerator pedal and start counting flashes to obtain the four-digit trouble code.

Long flashes (half seconds) indicate the first digit of the code; count the blinks one through nine and write down the first digit. (Ten blinks indicates a zero.) The next three digits follow in turn in the same fashion except with faster blinks (like a quarter of a second) and a 1 second pause between digits.

The ECM code repeats intself until you turn the ignition key to the OFF position, at which point the ECM resets itself to standard get-in-and-drive-the-car mode. You can look up the trouble codes in the FSM if you have a copy, or online. If you get four blinks of ten (0000), the ECM is indicating no malfunction.

Clearing
You can clear the code (and the annoying check engine light) by holding down the accelerator pedal for more than 10 seconds while in the above mode. When you release the pedal, the ECM erases the trouble code(s).

I hope this helps.

**micrapolis** · 02-25-2015, 02:14 AM

i never even knew this was a thing

its like those video game cheat rumors back in the day

anyone have a vid of this? interesting!

**Daox** · 02-25-2015, 11:47 AM

Very interesting. Thanks for sharing that tid bit.

**Howie** · 02-26-2015, 01:11 AM

We need to sticky this admin..

**lbarouf** · 02-27-2015, 10:59 AM

Originally Posted by Daox

Very interesting. Thanks for sharing that tid bit.

My pleasure. I didn't have my handy ODB-II reader close by, so I googled and it worked. So, what better place to share my finding that this community?

**AlphaMicra** · 02-27-2015, 03:19 PM

Nice. My old Dodge Neon from the 90's did a similar trick: Cycle the ignition key on and off 3 times one second apart, and the check engine light would start flashing OBD codes. Missed that in my Grand Am, really pleased that my Micra can do it.

**ptbo micra** · 02-27-2015, 06:00 PM

my 2000 Focus did this in a dash diagnostic mode, did some really cool things too. it would cycle through info on the trip meter from OBDII codes in hex format, to exact readouts of engine temp, speed, RPM etc. Was handy when the needle on the speedo went on the fritz.