Locate and open the "Diagnostic" box under the hood. It's between the battery and the fender. Below is
shown a representation of the pins inside the Diagnostic box:
The pins labelled "TEN" (which stands for "Test ENgine" by the way) and GND (ground) are the pins of interest. Make sure the ignition is OFF and use a paperclip to jumper the TEN and GND pins together.
E and J spec cars dont have a CE light .. conect a LED+Resistor or 12V-LED to the B+ terminal, and the free resistor - end to the FEN terminal. this will flash in place of the cel..
Turn on the ignition (do not start the car) and watch the CEL. After about 4-seconds, it will begin to flash any codes that may be stored. If there are no codes stored, the CEL will not flash (it will go out.)
Malfunction codes are generally 2-digit affairs although Mazda decided to get tricky. They include 2-digit codes that involve '0' (zero) as a digit. Code 02 is one example. Code 10 is another.
The codes are broken into a 10s digit and a 1s digit. The 10s digit is flashed first, followed by the 1s digit. The digits are distinguished by the length of time they flash the CEL. 10s digits flash the CEL on for 1.2-sec while 1s digits flash the CEL for 0.4-sec. Digits that are '0' (zero) flash the CEL exactly zero times.
Note how the presumably single-digit code '3' flashes the CEL for short-pulses only. This indicates the 10s digit is zero for this code. The image below illustrates what the CEL would do if, say, a code 24 were the only code present. Note that it's "dark" (off) for 4-seconds, then the code flashes (long flashes are 10s digits, short flashes are 1s digits). Since this is the only code, there is a 4-second pause between flashing sequences.
If you find yourself saying "Uh-oh"...
Notice in the above drawing that the TEN pin is located right next to the B+ pin... If you screw up and connect the B+ pin to the GND pin, you'll cause a short circuit when the ignition is switched on. You'll probably notice that the instrument cluster gauges don't work any more, along with other systems of the car. If you've done this, check the METER fuse in the fuse panel inside the car. Once you've replaced it, your gauges should operate as normal.
Interpreting the Codes:
There are quite a few codes. The following table shows the codes for the 1994 Probe GT (and a couple for the 1993) and what they mean. For FS (4-cyl) MECS-equipped engine codes, go here:
Code Circuit Diagnosed Memorized?
02 'NE2' crankshaft position sensor Yes
03 'G' camshaft position sensor Yes
04 'NE1' camshaft/crankshaft position sensor yes
05 Knock sensor Yes
08 Volume Air Flow sensor (VAF) Yes
09 Coolant temperature sensor (CTS) Yes
10 Intake air temperature sensor (IAT) Yes
12 Throttle position sensor (TPS) Yes
14 Barometric pressure sensor Yes
15 LHO2S inactivation error Yes
16 Exhaust gas recirculation (EGR) system Yes
17 LHO2S inversion error Yes
23 RHO2S inactivation error Yes
24 RHO2S inversion error Yes
25 Fuel pressure regulator control solenoid Yes
26 Canister purge solenoid No
28 EGR vacuum solenoid No
29 EGR vent solenoid No
34 Idle air control (IAC) solenoid No
41 VRIS #1 solenoid No
46 VRIS #2 solenoid No
67 LFAN relay (1993 only) No
69 ECTF sensor (1993 only) Yes