Check Engine Light Codes

Last updated: April 4, 2000

Date: Tue, 3 Jun 1997 00:38:45 -0500 (CDT)
From: Kevin L Tan (

Beside the battery is a little black box with the word "diagnosis" engraved on it. With the car turned off, open this box and bridge the terminals named "TEN" and "GND" ( i think the terminals are labeled under the cover of this box) with some wire.

Turn the car to the start position (do not start the car) and the check engine light should start flashing. Long flashes = 10 and short flashes = 1. Count the number of flashes and then refer to the shop manual in section F to reveal your magic code!


Date: Mon, 09 Jun 1997 20:54:17 -0500
From: (Dennis L. Myers, M.D.)

If your check engine light is coming on at idle you need to find out what it is telling you.

To do so for RX-7's from 1988 on, (with the engine off but fully warmed up) find the single green wire in the wiring harness just in front of the left front suspension tower, near the front ignition coil.

Ground the connector on this wire (the wire will be hanging free, without its connector hooked to another wire) on the chassis, using a jumper wire, etc.

Sit in the car and turn the ignition switch on WITHOUT STARTING THE CAR. Immediately watch the check engine light. If everything is OK, it will not light. If it starts flashing, count the flashes. It may stop flashing for a couple of seconds, then start again. Each of those series of flashes is for a separate engine fault code. Multiple codes will display in order from low number to high.

Have a paper and pen handy, and write them all down. To check again, turn the ignition off and then back on. It will repeat the cycle.

Identify the first (tens) and second(ones) digits of each code as follows: The first (tens) digit will display (flash) for about one second for each count, with a one-half second pause between counts. For example, if the first (tens) digit is three, there will be three separate one second long flashes, separated between by one-half second pauses.

There is then a 1.6 second pause between the last flash of the first digit and the beginning of the second (ones) digit.

The second (ones) digit counts flash for only one-half second each, with pauses of one-half second between them. For example, if the second (ones) digit is seven, then there will be seven flashes of one-half second, separated by pauses of one-half second.

In this example, the displayed code will thus be "37".

The system will then pause for four seconds before proceeding to the next code, if any.

To clear the stored codes from memory, disconnect the negative battery cable, then wait for 5 seconds. It is useful to do so even when you have just retrieved the codes, but not fixed anything yet, to be certain the codes (problems) persist. Stored codes could represent several different problems that have arisen at different times. Just drive the car a bit, and see which codes persist.

Obviously, once things are fixed, you need to clear the codes a final time to be certain it is in fact fixed, and to know that any new stored codes have occured after the fix.

Mazda RX-7 codes (from Haynes Computer Codes Manual #10205) are as follows:

1 Ignition coil (trailing side)
2 Crank position NE sensor
3 Crank position G sensor
5 Knock sensor
8 Airflow meter (AFM)
9 Water thermosensor
10 Intake air thermosensor (AFM)
11 Intake air thermosensor (engine)
12 Throttle sensor - full range
13 Pressure sensor - intake manifold
14 Atmospheric pressure sensor (built in ECU)
15 oxygen sensor 
17 Feedback system for O2 sensor
18 Throttle sensor - narrow range
20 Metering oil pump position sensor
23 Fuel thermosensor
25 Solenoid valve - pressure regulator control
26 metering oil pump stepper motor
27 Metering oil pump
28 Solenoid valve - EGR
29 Solenoid valve - EGR vent
30 Solenoid valve - split air bypass
31 solenoid valve - relief 1
32 Solenoid valve - switching
33 Solenoid valve - port air bypass
34 Solenoid valve -idle speed control (BAC)
37 Metering oil pump
38 Solenoid valve - accelerated warmup system and air supply valve
39 Solenoid valve - relief 2
40 Solenoid valve - purge control (auxilary port valve)
41 Solenoid valve - variable dynamic effect intake (VDI)
42 Solenoid valve - turbo precontrol
43 Solenoid valve - wastegate control
44 Solenoid valve - turbo control
45 Solenoid valve - charge control
46 Solenoid valve - charge relief control
50 Solenoid valve - double throttle control
51 Fuel pump relay
54 Air pump relay
65 Air conditioning signal
71 Injector - front secondary
73 Injector - rear secondary
76 Slip lockup signal
77 Torque reduced signal

Use the codes to direct you in fixing the car. Also remember that disconnected hoses, misrouted vacuum lines, or internal engine problems can be present without causing a code.


Date: Tue, 21 Mar 2000 13:33:50 -0800
From: "Ulen, Robert S" (

Engine ECU (Reference page F-20 of the Workshop Manual)

  1. With engine OFF, short "TEN" to "GND" terminals in the diagnostic plug (located on LH engine bay wheel well near battery). There is a "map" of the plug terminals located inside the plug lid.

  2. Turn the ignition switch ON, but do not start the engine.

  3. Read any stored trouble codes on the Check Engine light. If no codes are stored, the light will come on for approx. 2 seconds, then go out. If code(s) are stored, the Check Engine light will flash as follows to indicate code number. A Long flash represents the tens digit (10, 20, 30, etc.), and a short flash represents the ones digit (1 thru 9). Example: Long, short, short flash represents code 12. If any trouble codes are found, refer to page F-22 of the Workshop Manual for trouble shooting details.

  4. Cancel any stored trouble codes by turning OFF the ignition and disconnecting the negative battery cable for 20+ seconds. Press the brake pedal. Reconnect the negative cable to the battery. Ref. page F-64 of the Workshop Manual).


Date: Wed, 12 Nov 1997 13:27:56 -0700
From: "Nowhere Man" (

You can actually check the code yourself following these sneaky instructions. I list the meaning of the codes after these instructions.

First, at the diagnostic plug, located near the battery under the hood, short the TEN connector to a ground connector. I use:

                   \/      |
             o o   @ o     |
           o o o o o o o   |
            o o o o o o    | 
            o o @ o o o
            o         o

       Diagnostics Connector
       @=pins I use for the short

Once connected, turn ignition to ON. I've forgotten the order the digits flash, but here's the definition:

Second digit of service code (ones position)=number of times the check engine light illuminates for 0.4 seconds.

First digit of service code (tens position)=number of times the check engine light illuminates for 1.2 seconds.

Delay between codes is 4.0 seconds.

In other words, one long flash, followed by 5 short flashes (or 5 short flashes followed by one long flash, I can't remember the order) means a code 15. This will repeat again after 4 seconds (or, if your car is really screwed up, a different code will follow).

The ECU will cycle through all the service codes. After reach the last service code the ECU will go back to the first service code and repeat the cycle until the ignition is turned OFF. I wouldn't suggest you do this until the dealer has tried to fix your problem, but you can clear service codes:

Disconnect the negative battery cable. Wait at least 20 seconds then depress the brake pedal.

Reconnect the negative battery cable. Codes should be cleared. If not, a problem may still exist.

The codes are:

          02 - Crank angle sensor (NE signal) 
          03 - Crank angle sensor (G signal) 
          05 - Knock sensor 
          06 - Speedometer sensor 
          09 - Water thermosensor 
          11 - Intake air themosensor 
          12 - Throttle sensor (full range) 
          13 - Pressure sensor 
          14 - Atmospheric pressure sensor (in ECU) 
          15 - Oxygen sensor 
          16 - EGR valve (California only) 
          17 - Feedback system 
          18 - Throttle sensor (narrow range) 
          20 - Metering oil pump position sensor 
          23 - Fuel thermosensor 
          25 - Solenoid valve (pressure regulator control) 
          26 - Metering oil pump (stepping motor) 
          27 - Metering oil pump 
          28 - Solenoid valve (EGR) 
          30 - Solenoid valve (split air bypass) 
          32 - Solenoid valve (relief 1) 
          32 - Solenoid valve (switching) 
          33 - Solenoid valve (port air bypass) 
          34 - Solenoid valve (idle speed control) 
          37 - Metering oil pump 
          38 - Solenoid valve (accelerated warm up system) 
          39 - Solenoid valve (relief 2) 
          40 - Solenoid valve (purge control) 
          42 - Solenoid valve (turbo precontrol) 
          43 - Solenoid valve (wastegate control) 
          44 - Solenoid valve (turbo control) 
          45 - Solenoid valve (charge control) 
          46 - Solenoid valve (charge relief) 
          50 - Solenoid valve (double throttle control) 
          51 - Fuel pump relay 
          54 - Air pump relay 
          71 - Injector (front secondary) 
          73 - Injector (rear secondary) 
          76 - Slip lock up off signal 
          77 - Torque reduced signal 

Date: Sat, 11 Oct 1997 16:11:23 +0000
From: "Dave Girvan" (

> Does anyone know whether disconnecting the battery clears error
> codes from the car's computer? I can't find anywhere in the shop
> manual that mentions this.

Yes, it does. Disconnect the negative battery cable at the battery and then press the brake pedal for a second or two. When you re-connect the battery, all error codes will be flushed from the memory. Warning: If you have the stock radio, and the anti-theft feature is enabled, it will go into anti-theft mode. Make sure you have your 4 digit code to clear it handy! Or better yet, disable the anti-theft system, before disconnecting the battery. (Details in owners manual)


Date: Sat, 11 Oct 97 20:15:00 EST
From: "Houseman, Carl W. x1323" (

The diagnostic trouble code table, pages F-22 to F-25 in my 95 manual, has a column marked "Memorized" with yes/no indications for each code. Codes which are not memorized go away immediately upon battery disconnect. Codes which are memorized require you to step on the brake pedal with the battery disconnected, to clear them (procedure on page F-64).


Date: Fri, 10 Jul 1998 08:52:52 -0400
From: "Houseman, Carl W. x1323" (

Most codes are saved and can be read even when the light isn't on.

Go to When you get there you will see the term "MIL" which is Mazda language for Check-Engine light (Malfunction Indicator Lamp).

Date: Wed, 22 Sep 1999 19:38:40 +0200
From: =?iso-8859-1?Q?Bernd_Kl=FCsener?= (

Code 11 indicates either a faulty sensor (resistance wise) or a bad connection (connector, harness) between the sensor and ECU terminals 3L and 4D.

The intake air thermosensor is located on the underside of the extension manifold, which you need to remove to get at the sensor.

The sensor changes resistance as a function of intake air temperature. Test values are:

   at  68 deg Fahrenheit -----> 2.2 - 2.7 kOhm
at 176 deg -----> 0.29 - 0.35 kOhm

The ECU uses the signal from this sensor to decrease (hot intake air) or increase (cold air) the basic fuel amount for any given rpm/load point.

When error code 11 occurs, the ECU plays it safe by assuming 68 deg intake air temperature which, at this time of the year - means the air/fuel mixture is probably a little richer than necessary.

Date: Fri, 04 Feb 2000 13:09:59 -0800
From: Brodie (

After my vacuum hose job I ended up with a question that know one really could answer.

My car had a blue female electrical connector that I could not find the male to mate with it.

But after looking at my friends 94' touring and today looking at Rob Robinette's site I now know the answer.

California spec cars have an electrical sensor on the EGR valve that reports the valve's position to the ECU that will cause the Check Engine light to illuminate. The blue connector is only in use on California spec cars. Just in case anyone else was wondering.

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