P0340 on a Subaru: Causes, Fixes & Repair Cost

⚠️ Severe · not recommended to drive

The engine may not start, or it may stall while driving, so have the car towed if it won't start.

What P0340 means on a Subaru

On a Subaru, P0340 means the engine computer is getting no signal or a bad signal from the camshaft position sensor. Without camshaft position, the computer can't time fuel injection correctly, and the engine may refuse to start or may stall.

Is P0340 common on Subarus?

P0340 shows up on Subarus with higher mileage, often Outback, Forester, Impreza, and Legacy models. Subaru's boxer engines have a camshaft position sensor on each cylinder head, and these sensors fail with age and mileage. Oil leaks or wiring damage near the timing covers can also trigger it.

Commonly reported on: Outback, Forester, Impreza, Legacy.

Symptoms

Check engine light is on
Engine cranks but won't start
Engine stalls while driving
Rough running or loss of power

Common causes

most common: Failed camshaft position sensor
common: Damaged wiring or connector at the sensor
common: Oil contamination on the sensor
less common: Timing chain or timing belt issues

How to fix it

Fix	DIY?	Typical cost
Replace the camshaft position sensor	Yes	$50–150
Repair damaged sensor wiring or connector	Mechanic	$100–250
Have a mechanic check the timing belt or chain and its components	Mechanic	$600–1200