P0064 fault code: HO2S Heater Control Circuit High

P0064 means “HO2S Heater Control Circuit High” — a fuel and air metering fault in the powertrain.

Can I DIY?

Professional-only boundary. You may read the code; do not test heater resistance on a hot exhaust.

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 P0064

Do not drive. The computer sees too much voltage or current on a heated oxygen-sensor heater driver — often a short toward battery voltage — so the heater may be over-driven or the sense path is no longer trustworthy.

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

  • HO2S Heater Control Circuit High: Registration number
  • HO2S Heater Control Circuit High: Exact code P0064 and any companion codes
  • HO2S Heater Control Circuit High: Whether the engine management light is steady or flashing
  • HO2S Heater Control Circuit High: Any melted oxygen-sensor plug or burnt-loom smell you noticed from the side of the car
P00xxFuel and air metering
MOT fail riskif the warning light stays on

What does P0064 mean?

P0064 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 “HO2S Heater Control Circuit High”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed.

Will P0064 fail an MOT?

A lit malfunction indicator lamp fails MOT as a Major defect. P0064 does not add a separate named MOT test beyond that lamp and the emissions check.

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

P0064 — quick answers

Is it safe to drive with P0064?

Do not drive. We have no verified driving guidance for P0064. Do not drive until checked. A heater-circuit high fault is still an emissions-lamp issue; it is not permission to ignore a lit lamp.

Will P0064 fail my MOT?

A lit malfunction indicator lamp fails MOT as a Major defect. P0064 does not add a separate named MOT test beyond that lamp and the emissions check.

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.