MR2/Celica GT4 Fault codes
MR2/Celica GT4 Fault codes
Error codes are generated when the ECU receives an abnormal signal from a sensor. These error codes are stored, and can cause the check engine light to appear on the dashboard. MR2s destined for different markets (US, Japanese, Europe etc) can have different error codes, although the majority of error codes are shared across all variants.
Diagnostics connector and terminals
Locate the Diagnostic Box, on mine it is attached to the bulkhead behind the intake plenum. Open the lid, and on the inside of the lid you will see a diagram showing the location of each terminal. Look for TE1 and E1, and then using a short piece of wire or a "highly calibrated paper-clip!!" bent in a "U" shape, bridge the terminals TE1 and E1 (at your own risk).
Next switch on the ignition but don't start the car. Now look at the check engine light and you will notice it flashing. An ECU with no fault code stored will cause the check engine light to flash at constant pace.
If there is a fault code stored the light will blink with a serious of pauses, allowing you to read the code. All fault codes are 2 digit numbers. It is possible for more than one fault code to be stored at a time. Below is an example of how a check engine light would flash if codes 12, and 43 were stored. The "......" represent the length of time between flashes, and the "#" represents the flashes.
............#.....#..#.........#..#..#..#.....#..#..#......................#.....#..#.........#..#..#..#.....#..#..#........etc.
Take your time and study the check engine light, it is easy to read the fault codes. It is possible to see the check engine light from the back of the car, looking through the rear window.
To clear fault codes, you can either remove the EFI fuse, in the fuse box next to the battery, for a few seconds, or you can disconnect the negative cable from the battery.
Codes for MR2 SW20 Turbo 1991+ (GT4 codes may vary)
Codes Fault
1 Normal
12 RPM Signal 1
14 Ignition signal
21 O2 sensor signal
22 Coolant temperature signal
24 Intake air temperature signal
25 Lean error
31 Air flow meter signal
32 Air flow meter signal
34 Boost pressure
35 Turbo pressure sensor signal
41 Throttle position sensor
42 Speed sensor signal
47 Secondary throttle position sensor
52 Knock sensor signal
53 Knock management
This is not an exhaustive list, any code not listed here may be found using search engines etc.
"Life's goal is not to arrive safely at the grave in a well preserved body. But, rather to skid in sideways........
totally worn out and broken, shouting 'Holy ****, WHAT A RIDE!'"
FirebirdPhil
16-10-2016, 05:43 AM #1Unlike more modern cars with OBD2 ports the MR2/Celica GT4 didn't get that luxury, however there is an easy way to read engine fault codes:
Error codes are generated when the ECU receives an abnormal signal from a sensor. These error codes are stored, and can cause the check engine light to appear on the dashboard. MR2s destined for different markets (US, Japanese, Europe etc) can have different error codes, although the majority of error codes are shared across all variants.
Diagnostics connector and terminals
Locate the Diagnostic Box, on mine it is attached to the bulkhead behind the intake plenum. Open the lid, and on the inside of the lid you will see a diagram showing the location of each terminal. Look for TE1 and E1, and then using a short piece of wire or a "highly calibrated paper-clip!!" bent in a "U" shape, bridge the terminals TE1 and E1 (at your own risk).
Next switch on the ignition but don't start the car. Now look at the check engine light and you will notice it flashing. An ECU with no fault code stored will cause the check engine light to flash at constant pace.
If there is a fault code stored the light will blink with a serious of pauses, allowing you to read the code. All fault codes are 2 digit numbers. It is possible for more than one fault code to be stored at a time. Below is an example of how a check engine light would flash if codes 12, and 43 were stored. The "......" represent the length of time between flashes, and the "#" represents the flashes.
............#.....#..#.........#..#..#..#.....#..#..#......................#.....#..#.........#..#..#..#.....#..#..#........etc.
Take your time and study the check engine light, it is easy to read the fault codes. It is possible to see the check engine light from the back of the car, looking through the rear window.
To clear fault codes, you can either remove the EFI fuse, in the fuse box next to the battery, for a few seconds, or you can disconnect the negative cable from the battery.
Codes for MR2 SW20 Turbo 1991+ (GT4 codes may vary)
Codes Fault
1 Normal
12 RPM Signal 1
14 Ignition signal
21 O2 sensor signal
22 Coolant temperature signal
24 Intake air temperature signal
25 Lean error
31 Air flow meter signal
32 Air flow meter signal
34 Boost pressure
35 Turbo pressure sensor signal
41 Throttle position sensor
42 Speed sensor signal
47 Secondary throttle position sensor
52 Knock sensor signal
53 Knock management
This is not an exhaustive list, any code not listed here may be found using search engines etc.
"Life's goal is not to arrive safely at the grave in a well preserved body. But, rather to skid in sideways........
totally worn out and broken, shouting 'Holy ****, WHAT A RIDE!'"
Edit: Also some of them have ridiculous names, ie 'Secondary Throttle Position Sensor' is bogus, it's actually TRC or cruise control or something similar.
Also, the diagnostic box can be used for lots of other useful troubleshooting things, you can engage the fuel pump from it to check for fuel leaks / pressure without starting the engine, you can talk to a lot of the engine sensors from it, and also prevent the ECU from altering the ignition timing when trying to use a timing light.
And!! Not all error codes result in a check engine light, so this code checking process should always be your first port of call when troubleshooting. However it only talks to the main engine ECU (the EFI computer). There are different troubleshooting processes for the power steering ECU, ABS ECU, TRC ECU... you quickly start to see why ODB-II is a good thing!
And if you're in a pedantic mood, some MK2 MR2s *do* have ODB-II
As well as regional changes, automatic ECUs have different error codes to manual ones, etc. I have a definitive list somewhere from a GT4, which has the extra codes on it for the chargecooler system, I'll see if I can dig it out.
Edit: Also some of them have ridiculous names, ie 'Secondary Throttle Position Sensor' is bogus, it's actually TRC or cruise control or something similar.
Also, the diagnostic box can be used for lots of other useful troubleshooting things, you can engage the fuel pump from it to check for fuel leaks / pressure without starting the engine, you can talk to a lot of the engine sensors from it, and also prevent the ECU from altering the ignition timing when trying to use a timing light.
And!! Not all error codes result in a check engine light, so this code checking process should always be your first port of call when troubleshooting. However it only talks to the main engine ECU (the EFI computer). There are different troubleshooting processes for the power steering ECU, ABS ECU, TRC ECU... you quickly start to see why ODB-II is a good thing!
And if you're in a pedantic mood, some MK2 MR2s *do* have ODB-II
Quite clever things the ECU of a car.
"Life's goal is not to arrive safely at the grave in a well preserved body. But, rather to skid in sideways........
totally worn out and broken, shouting 'Holy ****, WHAT A RIDE!'"
FirebirdPhil
21-10-2016, 07:13 AM #3You are as always a fountain of knowledge!!
Quite clever things the ECU of a car.
"Life's goal is not to arrive safely at the grave in a well preserved body. But, rather to skid in sideways........
totally worn out and broken, shouting 'Holy ****, WHAT A RIDE!'"
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