Subaru Impreza 1992-2000 WRX & WRX STI Wiring Diagrams

A detailed wiring guide for the first-generation Impreza sports versions. Includes wiring diagrams, relay and fuse locations, sensor and control unit diagrams. Suitable for troubleshooting, repair and tuning of WRX and WRX STI cars with EJ20G, EJ20K, EJ25 ,EJ22  and EJ205 engines. Useful for car enthusiasts and Subaru repair specialists.

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1. Wiring and contacts:

Oxidation and damage to contacts - especially at the joints, sensor and control unit connectors, due to age and exposure to moisture.

Problems with the "ground" - poor contacts on the body lead to unstable operation of the electronics (dim headlights, ECU errors, unstable engine operation).

Wear and tear of wiring harnesses - often found in the engine compartment, near the door hinges and under the dashboard.

Blown fuses and relays - associated with overload of the electrical system or short circuits.

2. Electrics and lighting:

Failure of the generator - a weak point, especially under high load (additional audio system, headlights, heated glass).

Burnt out headlights and taillights - associated with the age of the wiring and unstable voltage.

Malfunctions of window lifters and heater motors - usually caused by wear of mechanisms and oxidation of contacts.

3. Sensors and control systems:

Crankshaft sensor (CKP) and camshaft sensor (CMP) failure – causes problems with starting the engine, jerks and misfires.

Lambda probe failure – causes increased fuel consumption and unstable engine operation.

Mass air flow sensor (MAF) problems – manifests itself in unstable speed, loss of power and “dips” during acceleration.

Knock sensor failure – can cause detonation, ECU errors and loss of power.

ABS failures – associated with contamination or damage to the wheel speed sensors.

Most electrical and wiring problems on a 1992–2000 Subaru Impreza are related to the age of the vehicle, component wear, and environmental influences. Regular diagnostics, contact cleaning, and preventive maintenance will help avoid serious problems.