OBD-II Code
P1086
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$80–$1,400
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$80 (oil change + screen clean DIY) to $1,400 (full AVCS hub + timing job on a chain-driven FB25).
P1086 is a Subaru-specific code meaning the AVCS (Active Valve Control System) on bank 1 is reading cam advance higher than the ECU commanded — the intake cam is over-advancing past the target angle.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP1086 is a Subaru-specific code meaning the AVCS (Active Valve Control System) on bank 1 is reading cam advance higher than the ECU commanded — the i…
P1086 is a Subaru-specific code meaning the AVCS (Active Valve Control System) on bank 1 is reading cam advance higher than the ECU commanded — the intake cam is over-advancing past the target angle. On EJ25, EJ20, FA20, and FB25 AVCS engines, the ECU commands cam phase from 0 to about 50 degrees of advance and reads actual position via the cam-position sensor; a deviation of more than 5-8 degrees from commanded for longer than ~2 seconds sets P1086.
Cheapest-first diagnostic ladder
- Check the oil. If it's black, gritty, or overdue by more than 1,000 miles, change it with the correct viscosity (5W-30 for most EJ25, 0W-20 for FA/FB) and a real Subaru or Tokyo Roki filter — AVCS is hydraulically actuated and 60%+ of P1086 cases on neglected EJ25s clear with a fresh oil change plus an Italian tune-up to circulate clean oil through the OCV.
- Scan AVCS live data with FreeSSM or a Subaru-capable tool: commanded advance vs. actual advance should track within 3 degrees at warm idle (~10 degrees commanded) and within 5 degrees at 3,000 rpm load (~25-35 degrees commanded). If actual lags commanded by more than 10 degrees, the OCV solenoid or its oil-feed screen is restricted.
- Pull the AVCS OCV (oil control valve, one per bank — bank 1 is passenger side on subies) and inspect the inline mesh screen behind it.
- Resistance-check the OCV solenoid winding: 6.9-7.5 ohms cold is the EJ-series spec; FA/FB run slightly different, check the WSM.
- Last and most expensive: the cam sprocket / AVCS hub assembly itself, which can wear or seize internally. Don't replace the OCV before checking for sludged AVCS oil-screen — every EJ25 with neglected oil changes shows AVCS faults from clogged screens, not bad solenoids, and a $400 solenoid won't fix a $5 screen blockage.
Vehicle-specific patterns2006-2012 Subaru Forester/Outback/Legacy/Impreza with the EJ25 SOHC AVCS (single-AVCS, intake-cam-only) is the most common P1086 ticket in North Amer…
- 2006-2012Subaru Forester/Outback/Legacy/Impreza with the EJ25 SOHC AVCS (single-AVCS, intake-cam-only) is the most common P1086 ticket in North American Subaru shops — the AVCS oil screen behind the OCV clogs with varnish from 7,500-mile oil change intervals and throws the code at 80,000-110,000 miles; pull the OCV, clean the screen with brake cleaner, change the oil, and the code clears 70% of the time.
- 2008-2014Forester XT / 2008-2021 WRX / 2004-2021 STI with EJ255/EJ257 dual-AVCS turbo engines see P1086 more often as a true OCV failure because the turbo's oil-shear is harder on the solenoid windings, but the screen is still the first check.
- 2013+FA20 (BRZ, 2015+ WRX) and 2011-2018 FB25 N/A (Forester, Outback, Crosstrek) use a redesigned OCV with a larger screen and see P1086 less frequently, but when they do it's usually a stretched timing chain retarding the actual cam position and confusing the AVCS reading — verify chain stretch with a borescope before condemning the OCV.
Estimated repair$80 (oil change + screen clean DIY) to $1,400 (full AVCS hub + timing job on a chain-driven FB25).
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