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Turbo & oil supply

P0011 / P0021 cam-timing codes and the oil control valves

The AVCS cam phasers and the turbo share the same oil circuit. A bank-1 (P0011) or bank-2 (P0021) timing code means the phaser is not getting oil pressure or the oil control valve is sticking, and it is often the first warning before the turbo dies.

CommonSeverity: MajorApplicability: Direct

Frequency basis: About five owners with these codes on the first page of a 98-reply legacygt.com thread, three of whom then lost the turbo; a 27-reply subaruoutback.org thread adds roughly six more. Forum consensus is that P0011 on an XT is highly correlated with an oil-supply problem.

Symptoms

  • Check engine light with P0011 (passenger side) and/or P0021 (driver side), cruise light flashing
  • Low power when merging, misfires on one bank, rough running only when warm
  • Turbo whine or a burnt-rubber smell at the same time means the turbo is probably already damaged
  • Oil level at or below the L mark in several of the reports

Causes found

  • Clogged banjo-bolt screens on the AVCS oil feed (same screens as the turbo feed) or a clogged turbo screen dropping pressure to the whole circuit
  • Sticking or lazy oil control valve (OCV, Subaru 10921AA020)
  • Dirty or low oil; a cracked oil pickup tube was raised as a cause on Legacy GTs
  • A failing turbo bearing dropping oil pressure so the OCV cannot modulate (member theory)

Check in this order

  • Stop driving the car until the cause is found; low oil flow to the phasers means low flow to the turbo
  • Check oil level and condition first; change it if it is dark or overdue
  • Both banks at once points to oil supply; one bank points to that side's OCV or its screen
  • Pull and inspect the AVCS banjo screens and the turbo feed screen
  • Check the OCV connectors are seated; log AVCS advance on both banks with an AccessPort or BtSsm, they should be within about 2 degrees of each other

What fixed it

  • Cleaning the OCV with solvent cleared the code for about 450 miles for one owner; he called it a band-aid and fitted a new valve (about $110 at the dealer)
  • New OCV plus cleaned screens fixed cars caught early
  • Cars that kept driving on the code ended up with a dead turbo, and in two reports burnt valves or low compression on cylinder 4
  • An oil change alone sometimes clears it, but owners warn not to treat that as a fix

References on this site

OEM parts

  • 10921AA020Oil flow control valve (AVCS OCV), part number as cited by Fred Beans Subaru in the thread
  • 14445AA090Union screw and filter assembly (banjo bolt with screen)
  • 13320AA001Sprocket assembly, camshaft intake right (AVCS phaser)
  • 13322AA001Sprocket assembly, camshaft intake left (AVCS phaser)

Sources

Forum threads are owner reports, not factory findings. Counts are from the threads and complaint records read for this page; read the sources before buying parts.

  1. 1.
    P0011, P0021, Missfire, OCV or Oil flow Control Valve

    legacygt.com · Forum thread · 2010–2012, 98 replies, OCV cleaning vs replacement walkthrough

  2. 2.
    P0011, a check engine story

    subaruoutback.org · Forum thread · 2012–2014, 2005 XT, code preceded turbo failure

  3. 3.
    Oil Control Valve - 05 Outback XT - Maintenance replacement or cleaning?

    subaruoutback.org · Forum thread · 2014, preventive discussion

  4. 4.
    Yet another P0011 and P0021 problem thread

    nasioc.com · Forum thread

  5. 5.
    P0021 on 2005-2019 Subaru Legacy / Outback: Camshaft Timing Fixes

    go-parts.com · Article · vendor guide; cites a TSB on banjo-filter removal, bulletin number unverified