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Fault code

P0201 fault code.

This code comes up with one known fault.

Generic code

Code type

Engine and drivetrain

System

Electrical fault of the cylinder 1 injector

The engine control unit measured a fault in the electrical circuit of the cylinder 1 injector. An open circuit, a short or a failed injector can all cause it. A code for a single cylinder often comes with a misfire code as well.

The code tells you what the control unit measured, not which part has failed. The same code has several possible causes.

Which known faults it comes up with

Injector failure: metal debris from the pump, or back-leak into the oil

expensive

The injectors fail above 100 000 kilometres, and how quickly depends on the quality of the fuel and on the servicing. Three paths lead here, and each one is checked differently at a viewing.

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The nozzle can clog from poor fuel. As the high pressure pump wears, metal debris gets into the system and destroys the injectors; that can be seen in the fuel filter. And the Delphi injectors from before 2010 leak through a back-leak and dilute the oil with diesel; there is a back-leak test for that.

The symptom is an uneven idle, hard starting, jerking, lack of power and black smoke, along with a tapping noise and the injection warning light. In the fault memory the codes from P0201 to P0204 appear, cylinder by cylinder.

An injector that atomises poorly also fills the particulate filter faster, because it produces more soot. If an injector fails badly, the piston can even melt or burn through.

An injector costs around 100 pounds each, and it is worth replacing them together as a set. Reconditioned parts are also available, and they are noticeably cheaper.

above 100,000 km

What to check

  • Open the fuel filter, or ask for the last change: metal debris means the pump is wearing
  • Ask for an injector back-leak test: that shows up an injector leaking backwards
  • Watch the engine at idle: uneven running and a tapping noise belong here
3 more steps in the write-up

Information, not an expert opinion

We write the descriptions, and we put the source next to them. A person reviews them before they go out. They are still information, not a technical expert opinion.

  • A fault on the list does not mean the car you are looking at has it.
  • A fault missing from the list does not mean the model is fault-free. Write-ups are made model by model. Not all of them are done.
  • You decide whether to buy. This is no substitute for an inspection. That needs a workshop and a history check.
Details in the terms