How to check the ECU for error codes Print Disclaimer Please note that I am not a mechanic by trade and that I nor Turbocelica.nl can be held responsible for any damage, injuries or death caused by work you perform using this website as a guideline. Make sure the engine is at normal operating temperature, the gearbox in neutral and the battery voltage at least 11 V. Parts and tools needed Paperclip or electrical wire (~5 cm) Location Open the bonnet and locate the diagnosis terminal behind the strut tower: Open the cap. The diagram inside shows which connector is what. Connect E1 and TE1 with the piece of wire: Turn the ignition key to 'ON' but do not start the engine. The stored ECU error code will be shown by the blinking pattern of the Check engine light (CEL) which looks like this: If the CEL blinks in a continuous pattern (0.25 sec. on, 0.25 sec. off, 0.25 sec. on, etc.) there are no error codes. If there is a code, the intervals change. If there are multiple codes, indication begins with the lowest number and continues to the highest code: Remove the wire from the diagnosis terminal and put the cap back on. Resetting the ECU Besides code 51 and 53, all error codes are stored by the ECU until it is reset. After the problem is solved/repaired, there are two ways of resetting the ECU. Make sure the ignition key is turned to 'OFF'. 1) Pull the EFI fuse (15A) for 30 sec. 2) Disconnect the negative terminal of the battery (keep in mind radio and clock will also be reset) Check if the ECU is reset successfully with another check. If there are no error codes, the CEL should go out after starting the car. A rough idle after the first start is normal when resetting the ECU by pulling the EFI fuse. During the first drive this will be sorted by the ECU. Job done! Related links How to.. ST185 ECU error codes Top