P0079 fault code: Exhaust Valve Control Solenoid Circuit Low

P0079 means “Exhaust Valve Control Solenoid Circuit Low” — a fuel and air metering fault in the powertrain.

Can I DIY?

Professional-only boundary. Do not probe an exhaust-cam solenoid on a hot manifold.

Do not DIYReviewed page boundary
ToolsSpecialist equipment

This is the conservative boundary from the reviewed code record. This page has no frozen site-wide safety grade, so it does not publish a repair route.

What to tell the garage about P0079

Do not drive. The exhaust-valve control solenoid is seeing a low circuit, so it may not move. Exhaust cam timing then stays on its rest stop instead of following the exhaust map.

Take these reviewed, code-specific details with you. They help the garage confirm the fault without turning this page into a repair procedure.

  • Exhaust Valve Control Solenoid Circuit Low: Registration number
  • Exhaust Valve Control Solenoid Circuit Low: Exact code P0079 and any companion codes
  • Exhaust Valve Control Solenoid Circuit Low: Whether the engine management light is steady or flashing
  • Exhaust Valve Control Solenoid Circuit Low: Whether you smelled exhaust in the cabin after the lamp came on
P00xxFuel and air metering
MOT fail riskif the warning light stays on

What does P0079 mean?

P0079 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P00xx block, which covers fuel and air metering. The stored description is “Exhaust Valve Control Solenoid Circuit Low”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0079 fail an MOT?

MOT fails the vehicle if the engine management light is on. Circuit-low exhaust-valve control is not a separate MOT electrical heading.

Before booking your test, check what usually fails on your car: see our MOT pass rates by make and model, built from 33.1 million DVSA tests.

Related guides

Car diagnostic test cost: compare the scopeUK booking marketplaces currently publish diagnostic averages of about £52–£65. Engine management light on: steady or flashing?A steady engine management light means the computer has stored a fault. Drive with caution and get the code read. A flashing light is different — stop when it is safe.
P0001Fuel Volume Regulator Control Circuit/Open P0002Fuel Volume Regulator Control Circuit Range/Performance P0003Fuel Volume Regulator Control Circuit Low P0004Fuel Volume Regulator Control Circuit High P0005Fuel Shutoff Valve 'A' Control Circuit/Open P0006Fuel Shutoff Valve 'A' Control Circuit Low P0007Fuel Shutoff Valve 'A' Control Circuit High P0008Engine Position System Performance

P0079 — quick answers

Is it safe to drive with P0079?

Do not drive. P0079 has no verified driving guidance. Treat as do not drive until checked. A low exhaust-cam solenoid circuit can leave emissions and idle in a default state with the lamp on.

Will P0079 fail my MOT?

MOT fails the vehicle if the engine management light is on. Circuit-low exhaust-valve control is not a separate MOT electrical heading.

Fault-code identifiers are standard diagnostic facts. Their explanations and diagnostic guidance on this site are original editorial summaries, not reproduced SAE wording. MOT defect rules reflect the DVSA MOT inspection manual (2026). This page is general guidance for UK drivers, not a substitute for a professional diagnosis.