Subaru Legacy: EJ25T AVCS cam gear bolt loosening

The turbocharged EJ255 in the BM/BR Legacy GT uses Subaru's Active Valve Control System. The intake camshaft sprocket retaining bolt and gear can work loose due to oil pressure pulsing and high-load cycling. A loose AVCS cam gear produces a ticking or knocking noise and triggers cam position fault codes. If the gear slips significantly, cam timing is lost and engine damage can follow. The same fault is extensively documented on WRX of the same generation sharing identical hardware.

• Ticking or knocking from the top of the engine, often most apparent at idle
• Check engine light with intake cam timing codes such as P0340 or P0345
• Rough idle or hesitation on acceleration
• Noise intensity changes with engine RPM

1. 1

   Scan for cam position sensor fault codes before purchasing.

2. 2

   Listen carefully at idle for ticking or rattling from the valve cover area.

3. 3

   Ask for service records showing AVCS inspection history.

4. 4

   Confirm whether the cam gear retaining bolts have been re-torqued or replaced with upgraded hardware as a precaution.

$800 to $1,600 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the car had any cam timing faults or check engine lights?”
• “Has the AVCS cam gear retaining bolt been inspected or replaced?”
• “Is the car running any aftermarket tune or boost modifications?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.