Locate and open the "Diagnostic" box under the hood. It's by the firewall. Below is shown a representation of the pins inside the Diagnostic box:
http://home.golden.net/~trinity/malf/diag21.gif - IMAGE NOT AVAILABLE
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.
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.
The diagram below illustrates graphically how two typical malfunction codes might be flashed out.
http://home.golden.net/~trinity/malf/celflsh.gif - IMAGE NOT AVAILABLE
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.
List of codes and what they correspond to:
- 02 'NE2' crankshaft position sensor
03 'G' camshaft position sensor
04 'NE1' camshaft/crankshaft position sensor
05 Knock sensor
08 Volume Air Flow sensor (VAF)
09 Coolant temperature sensor (CTS)
10 Intake air temperature sensor (IAT)
12 Throttle position sensor (TPS)
14 Barometric pressure sensor
15 LHO2S inactivation error
16 Exhaust gas recirculation (EGR) system
17 LHO2S inversion error
23 RHO2S inactivation error
24 RHO2S inversion error
25 Fuel pressure regulator control solenoid
26 Canister purge solenoid
28 EGR vacuum solenoid
29 EGR vent solenoid
34 Idle air control (IAC) solenoid
41 VRIS #1 solenoid
46 VRIS #2 solenoid
