If you can visit one autozone shop, they can read or scanning your OBD codes.
Codes are displayed on digital odometers on newer models. On many 2001 and newer models, holding in the trip odometer
reset button while turning the key to RUN will start a self test, with
a readout on the odometer. It will also activate all instrument panels,
one at a time. We do not know if this will show computer codes, or
whether it only tests the instrument panels.
At the end, it may show
a few odd codes that are firmware versions and not error codes.
On most cars, the codes will read out if the engine light is on -
all you have to do is put the key into the RUN position.
Normally, to get codes, you put the key on OFF and then
rapidly do OFF-ON-OFF-ON-OFF-ON (on some cars you have to do four or
five, not three, OFF-ON cycles). On our test 2002 car, the key did not
go back to unlock, so it was ACC-ON-ACC-ON-ACC-ON.
- You may have to have the parking brake firmly set for the
codes to show! (Thanks, Steven Midway)
- Jon Yoon: The 1998 Caravan does the same check engine light
code trick, but it also does an instrument diagnostic check if you hold
the trip and reset buttons and turn the key to the run position and wait
5 seconds. This helped me figure out that my input and output speed
sensors were broken but the actual speedometer dial could move.
- For the 1999 Jeep Grand Cherokee and up, you do the switching the
key on and off 3 times, but not quickly. You turn it to on so the
odometer turns on, turn it off, and then back on, wait for the light to
turn on, etc. On the fourth time you'll get a code, or you'll get the
word "done." (Monica MacDonald)
A loose gas cap may light up the Check Engine light! (Thanks, Lyn
RESET THE COMPUTER
- When the computer indicates major failure, it can activate
Limp In mode, which guesses about data to compensate for sensor failure,
allowing you to get the car to a mechanic. One major symptom of this is
the transmission sticking in second gear. This is a feature!
- 2002 Ram, put transmission in neutral, parking brake on, then do
the acc-run key sequence 3 times.
- Dan Stewart wrote about the 1999+ Voyager/Caravan with digital gear
- There are 2 functions that can be accomplished with the key-on
sequence. Get Diagnostic Trouble Codes by placing the key into the
ignition. Push and hold the both the "Trip" and the "Reset" buttons
with the left hand and turn the key to the "ACC" position (first
position between "LOCK" and "RUN"). Continue to hold both buttons in
and count to 5. Release both buttons, display should read trip mileage
instead of total mileage. Push the "TRIP" button and the odometer will
display DTC'S in rotating sequence instead of displaying total mileage.
- The second function is an instrumentation diagnostic. Place
key into ignition, press and hold both "TRIP" and "RESET" while turning
the key to the "RUN" position. Continue to hold both buttons in
until odometer displays "CODE". Release buttons. The
display will then display "999". Afterward it will display "CHECK
0" and test the analog gauges. It will then display "CHECK 1" and
test the digital displays
Normally the computer will eventually reset itself; you can also use a
scan tool. (See our transmission repair page for information on
resetting the computer's transmission information.) Disconnecting the
battery for a few minutes generally resets the computer, though it also
means losing clock settings.
Sid Willoughby wrote: “To clear the check engine light on a 2002
Dodge Ram once the problem is resolved. Start the engine and drive
forward then in reverse (you only have to move the truck a few feet in
each direction) the turn the ignition off. Do this sequence three times.
When you start the vehicle the fourth time the check engine light
should go out.” (This procedure may well work on other vehicles.) CODE LIST 2001
which covers some vehicles from the late 1990s as well as newer ones. It
shows the longer codes starting with the letter P.
Hope this help (remember comment and rated this).