Subaru Impreza 2007-2014 WRX & STI System Wiring Diagram

This page provides a complete electrical diagram for the 2007-2014 Subaru Impreza WRX and STI models. Includes:

System Wiring - a diagram of the connections of all electrical components.

Fuse and Relay Boxes - location and function.

Ground and Power Circuits - for troubleshooting.

Engine and Chassis Electrical - control systems, sensors, and main circuits.

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• Impreza GR, GH, GE, GV 2007-2014 Workshop Manual

1. Engine sensors and electronics

🔧 Error P0335/P0340 – Crankshaft and camshaft position sensors

The engine may have trouble starting, stalling, or displaying an error.

Cause: sensor contamination or wear, broken wiring.

✅ Solution: cleaning the sensor, checking the wiring, replacing.

🔧 Error P0171/P0172 – Mass Air Flow Sensor (MAF)

The car jerks, unstable speed, check engine.

Cause: sensor contamination, air leak.

✅ Solution: flushing the MAF sensor, checking the intake for leaks.

🔧 Malfunction of oxygen sensors (lambda probes)

Increased fuel consumption, unstable idle.

✅ Solution: replacing the lambda probe (better than the original).

🔧 Electronic throttle (ETC) is glitching

The car may lose traction, the check engine light may come on.

Cause: dirty throttle, wiring problems.

✅ Solution: clean the throttle, check the connectors.

2. Electrical equipment and fuses

🔧 Fuses and relays burn out

A common problem is the fan or fuel pump relay melting.

✅ Solution: check the circuits for short circuits, replace the relay with a reinforced version.

🔧 Flashing cruise control light + check engine

Usually associated with a sensor error (MAF, lambda, throttle).

✅ Solution: OBD-II diagnostics, check error codes.

3. Lighting and dashboard

🔧 Burnt out low beam lamps

The lamps often fail (especially on the STI).

✅ Solution: Install Osram Night Breaker bulbs, check the ground.

🔧 Failure of the instrument panel backlight

Often associated with oxidation of contacts in the fuse box.

✅ Solution: Clean contacts, replace burnt-out bulbs.

4. Wiring problems

🔧 Fraying of the harness under the hood (especially on STI)

Over time, vibrations can damage the insulation.

✅ Solution: Protect wires with corrugated pipe, solder damaged areas.

🔧 Oxidation of the ground (negative wire)

Possible electrical glitches, long start-up.

✅ Solution: Clean and replace the ground with reinforced cables.