BMW vehicles manufactured between 1989 and 1994 come with a built-in self-diagnostic system designed to identify injection faults. When a fault is detected, the Electronic Control Unit (ECU) stores a corresponding code in its memory until the vehicle battery or ECU is disconnected, the engine is started 60 times without a recurrence of the fault, or the ECU memory is cleared using specific tools like the Bosch KTS300, CARSOFT BMW software, or the CS1000 BMW hand scanner.
To access the FAULT CODES stored in the ECU memory, follow these steps:
Turn the ignition switch to the engine run position.
Depress the gas pedal to the floor 5 times.
The CHECK ENGINE light will then display the FAULT CODES, starting with the lowest number first. Each FAULT CODE consists of 4 digits, separated by a short pause (e.g., blink pause blink blink pause blink pause blink translates as 1 2 1 1).
