P0A08 fault code: DC/DC Converter Status Circuit High severity

P0A08 means “DC/DC Converter Status Circuit” — a hybrid propulsion fault in the powertrain. If the car enters ready mode and drives normally, short trips are fine; do not ignore isolation warnings. Typical UK repair cost: £90–£3000 depending on the underlying cause.
HighSeverity
P0AxxHybrid Propulsion
£90–3000Typical UK repair cost
MOT fail riskif the warning light stays on

What does P0A08 mean?

P0A08 is a generic (SAE standard) powertrain code reported by your car’s engine control unit. It sits in the P0Axx block, which covers hybrid propulsion. The stored description is “DC/DC Converter Status Circuit”. The code itself tells you which circuit or system tripped the fault — not always the exact part that failed, which is why a short diagnosis pays for itself before replacing components.

Symptoms you may notice

  • Hybrid or EV warning light on the dash
  • Reduced electric range or the engine running constantly
  • Car refuses to enter ready mode

Most common causes

  1. Ageing high-voltage battery cells or balancing faults
  2. Cooling system faults for the battery pack
  3. 12V auxiliary battery failure (surprisingly common trigger)
  4. Isolation faults in high-voltage wiring

How to diagnose P0A08 yourself

  1. Test the 12V auxiliary battery first — a weak 12V battery causes many phantom hybrid codes
  2. Read hybrid battery block voltages with a capable scanner
  3. High-voltage repairs belong with a hybrid-qualified technician
Tools that read and clear P0A08

A basic code reader confirms the fault; a full-system scanner shows the live data you need for the steps above.

Will P0A08 fail an MOT?

Hybrid and EV warning lamps are inspected at MOT — an illuminated propulsion battery warning is a Major defect.

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.

Typical UK repair costs

OutcomeTypical cost (parts + labour)
DIY: read code + basic checks£0 (scanner assumed)
Independent garage diagnosis£30–£60
Typical repair range for this fault£90–£3000
Main dealer equivalent£135–£5400

Costs are indicative UK ranges for independent garages in 2026. Main dealers typically charge 40–80% more.

Diagnose the symptom, then price the repair

Car diagnostic test cost UK (2026): scan vs actual diagnosis£40–£100 is typical for an independent first assessment — but a code read is not the same as finding the cause.
P0A00Motor Electronics Coolant Temperature Sensor Circuit P0A01Motor Electronics Coolant Temperature Sensor Circuit Range/Performance P0A02Motor Electronics Coolant Temperature Sensor Circuit Low P0A03Motor Electronics Coolant Temperature Sensor Circuit High P0A04Motor Electronics Coolant Temperature Sensor Circuit Intermittent P0A05Motor Electronics Coolant Pump Control Circuit/Open P0A06Motor Electronics Coolant Pump Control Circuit Low P0A07Motor Electronics Coolant Pump Control Circuit High

P0A08 — quick answers

Is it safe to drive with P0A08?

If the car enters ready mode and drives normally, short trips are fine; do not ignore isolation warnings.

Will P0A08 clear itself?

If the underlying fault stops occurring, most ECUs extinguish the light after around 40 healthy warm-up cycles — but the code stays stored as history. Fix the cause, clear it with a scanner, then confirm it stays away over a full drive cycle.

How much does it cost to fix P0A08 in the UK?

Typically £90–£3000 at an independent garage depending on which cause you confirm. Diagnosing it yourself with a scanner avoids a £30–£60 diagnostic fee and stops parts being replaced on guesswork.

Will P0A08 fail my MOT?

Hybrid and EV warning lamps are inspected at MOT — an illuminated propulsion battery warning is a Major defect.

Code definitions follow the SAE J2012 standard. 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.