P0204 on Land Rover: How to Diagnose & Fix
Injector Circuit/Open - Cylinder 4
1 Land Rover model · 1 documented issue · $30-$250 repair
P0204 on Land Rover by model: symptoms, diagnosis and fix
A hardening rocker-cover/injector seal lets engine oil into the under-cover injector harness. Oil then travels by capillary action ALONG the copper strands inside the loom, past the rocker-cover connector and down the engine loom — sometimes all the way to the ECU's red plug. Once oil corrupts the injector signal path you get bizarre, intermittent faults: misfires, rough idle, hard/no-start, cutting out and random fault codes that chasing sensors won't fix. It is one of the most common and most misdiagnosed Td5 electrical gremlins.
Common Symptoms
- Intermittent misfire or rough idle
- Hard starting, no-start, or random stalling
- Erratic / non-repeatable fault codes
- Oil visible in injector connectors or at the ECU red plug
How to Fix
The reliable cure restorers use is to REPLACE the injector harness (part AMR6103, correct for Defender Td5 1999–2006) rather than just clean it — cleaning only buys time because the contaminated strands keep wicking. Fit a fresh rocker-cover gasket and injector seals at the same time to stop oil re-entering, and inspect/clean the ECU red plug for migrated oil. Cheap part (~£30) and roughly a 30-minute job, but it permanently kills a fault that otherwise reappears.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- OEM AMR6103 Td5 injector harness with selectable 10P/15P rocker-cover gasketOEMAMR6103 plus ERR7094 early or LVP000020 later gasket
Replace an oil-contaminated or electrically failed under-rocker injector harness and renew the correct rocker-cover gasket Fitment/availability: 1999-2006 Defender Td5; select early 10P or later 15P by the actual installed cylinder head,…
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Sources for this issue (3)
P0204 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0204 mean on a Land Rover?
P0204 stands for "Injector Circuit/Open - Cylinder 4." This code means the Engine Control Module detected an electrical problem (open circuit or out-of-range resistance) in the fuel injector control circuit for cylinder 4. The ECM controls each injector through its own circuit and monitors it to confirm proper operation. P0204 indicates the computer isn't seeing the expected electrical response from cylinder 4's injector, so that cylinder may not be getting the correct fuel. You'll often notice a misfire, rough running, and a loss of power tied to cylinder 4. On Land Rover it is documented across 1 model: Defender.
What are the most common causes of P0204?
The most common causes of P0204 are: Damaged or corroded injector connector at cylinder 4, Open or shorted wiring in the injector control circuit, Failed (electrically open) fuel injector on cylinder 4, Loose or backed-out connector pin, Poor ground or power feed to the injector, Faulty injector driver inside the ECM/PCM, Chafed harness causing intermittent open. The specific cause varies by vehicle.
How much does it cost to fix P0204 on a Land Rover?
Published repair estimates on Land Rover range from $30 to $250 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0204 on a different make?
View P0204 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.