How to Read OBD Codes – mr2 sw20

Overall Toyota MR2’s are actually quite reliable but of course they have their problems as any car does. They have a very early OBD system but can manually be read. I’m sure some of you may have seen a post about common problems with SW20 mr2s but I wrote that more than information to someone thinking of buying a mr2. This post shall have a little more depth and aimed at someone who already owns a mr2 and is looking to solve a problem with their car.

How to Read Fault Codes

Fault codes (otherwise known as diagnostic trouble codes) are generated when receives and abnormal or not possible signal from a sensor. These codes are remembered and can cause the EML (engine management light) to illuminate. Each code represents each problem signal from each sensor, but as the mr2 was built for different markets, some different models have a few different codes.

Modern cars use what is known as “OBD2” which allows you to connect a diagnostic tool to the OBD port and read each code from the tool itself. Older cars do not have this but some have a similar set up.OBD scanner tool

How to read fault codes

The fault codes can be extracted from the ecu by linking to terminals TE1 and E1 of the diagnostic connector (offside rear part of the engine bay) to each other, whilst the ignition is completely off. If you don’t known which terminals these are there is a diagram on the cap of the connector, if you have lost this, leave a comment and I will explain which terminals are TE1 and E1.

Then switch the key to ignition 2 (the second position or one before cranking the engine). This should cause the EML to flash, if this flashing is continuous and steady then, good news! It means you have no known fault codes.

The fault codes exist as two numbers (e.g 39 or 57). If you do have one of these it will cause the same light to blink a certain number of times, relative to the number, then a pause then blink again for the next number. As it is possible for more than one fault code to be stored at the same time it will give an extra long pause before flashing again for the next fault code.

Watching and counting the flashes allows you get the number of each fault code and then look up what each one means. Not all car models have the same codes that mean the same thing, but after some research on the internet I have found a rough guide to most fault codes for the mr2.

Some Code NumbersEngine Management Light

Codes — Item

2/31 Inhalation pipe pressure meter

3/14 Ignition indicator (except cars with DLI, DRD)

3/14 Ignition indicator (for cars with DLI, DRD)

4/22 Water leak indicator

5/21 Dx indicator

6/12-3 Tachometer

7/41 Throttle position sensor (cars with linear sensor)

8/24 Inhalation temperature sensor

9/42 Speedometer

10/43 STA indicator

11/51 Switch

11 +B (except cars with step motor type ISCV)

11 +B (for cars with Step motor type ISCV)

23 Evaporator temperature indicator

31,32 Air flow meter (except cars with carman whirlpool air flow meter)

31 Air flow meter (for cars for carman meter)

32 Atmospheric pressure meter (7M-GTEU)

33 ISCV meter

34 Circulation pressure supply

31 Circulation pressure supply

35 Turbo pressure sensor

52,53 Knock indicator (sensor)

54 Intercooler

01 Data communication

These may not all be correct but just what I could find after searching for the codes online to use as a guide.

How to delete fault codes

Once you read your fault codes and hopefully later fixed your cars problem, they can be deleted so the EML will no longer light up. To do this you can either remove the EFI fuse for a few seconds from the fuse box near the battery or even disconnect your negative cable from the battery for a short amount of time. This should reset and get rid of any old stored codes.

Any help or questions?

Please feel free to leave any comments, questions or advise 🙂






2 Replies to “How to Read OBD Codes – mr2 sw20”

  1. Hi I have a 1993 3sgte with management light on when I test it it flashes continuos tell me no fault I reset and it comes straight back on any ideas what this could

    1. Hi, thanks for the comment. I have found a useful link for you. But presuming you are checking for fault codes correctly then there is two causes, the light should be on while the ignition is on but switched off when the engine is running, its inside the ecu on the earth side of the light that switches it off, if there is a short to ground then this could cause the light to come on when it should not be, other than the ecu itself could be on its way out and/or needing repaired from capacitors leaking basically. The second scenario would require looking in to to find if a capacitor can be replaced or if it has caused too much damage to the board already. Here is the link, Let me know how you get on or if you need any more help! Thanks

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