Bob's Mechanical Repairs

Toyota P0301

Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email [email protected].

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Cylinder 1 misfire on Toyota — usually coil pack on 1.8 VVT-i / 2.0 D-4D, but on the 1.4 D-4D injector failure is very common.

Toyota P0301 — Cylinder 1 misfire on Toyota — usually coil pack on 1.8 VVT-i / 2.0 D-4D, but on the 1.4 D-4D injector failure is very common. Typical UK independent garage cost: £50–£1200.

What actually causes P0301 on a Toyota

Toyota 1.4 D-4D (1ND-TV) suffers chronic Denso injector failure — copper sealing washers leak, combustion gas blowback carbons up the injector seat, and you get a misfire that sounds like a tractor at idle. Coil packs are a frequent fail on the 1.8 VVT-i petrols at 80,000+ miles.

Toyota engines that log P0301

  • 1.4 D-4D (Yaris, Auris, Corolla)
  • 1.8 VVT-i (Auris, Corolla, Avensis)
  • 2.0 D-4D (Avensis, RAV4, Verso)

How we diagnose P0301 on a Toyota

  1. Swap coil pack from cylinder 1 to cylinder 2 — if misfire follows, replace coil
  2. On 1.4 D-4D, inspect injector copper washers and seat for blowback (black carbon ring)
  3. Compression test if no electrical/injector cause found
  4. Live data: check fuel trim and short-term fuel correction per cylinder

The common misdiagnosis to avoid

Replacing a 1.4 D-4D injector without machining the injector seat is a 6-month fix — the carbon damage to the head seat must be addressed at the same time.

Toyota P0301 repair cost in the UK

Expect £50–£1200 including parts and labour at an independent garage. Main-dealer quotes on Toyota are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.

Bob's workshop tip

On 1.4 D-4D always replace all 4 injector copper washers as a set — it's a £12 part and saves a full repeat job next time.

Codes usually seen alongside P0301 on Toyota

  • P0300
  • P0302
  • P0303
  • P0304

Symptoms drivers report with P0301

  • Engine 'juddering' like a wet dog when you try to overtake on the A9.
  • The car 'kangaroos' at low speeds, especially when the engine is stone cold.
  • The EML (Engine Management Light) is flashing at you—that's a 'stop now' warning for your catalytic converter.
  • A distinct 'put-put-put' sound from the exhaust pipe at idle.
  • Massive loss of power, feels like you're towing a caravan that isn't there.

Repairs that clear P0301

  • Replace spark plug
  • Swap coil pack
  • Injector test
  • Compression test

For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0301 guide.

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