P0201
PowertrainCylinder 1 Injector Circuit Malfunction
Cylinder 1 fuel injector circuit has a fault. The ECU isn't getting the expected response from injector 1's electrical circuit, suggesting the injector coil, connector, or wiring is the issue.
ⓘ Information only. This page provides general educational information about fault code P0201. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0201 mean?
P0201 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 1 Injector Circuit Malfunction.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light, often with a misfire on cylinder 1 (P0301)
- • Rough running, particularly noticeable at idle
- • Loss of power
- • Possibly hard starting
- • On diesels: knocking or rough running at low loads
Possible causes
Causes commonly associated with P0201, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Failed injector electrical (open or shorted coil)
- 2. Damaged connector at the injector, often from heat or oil contamination
- 3. Wiring fault to the ECU, sometimes where the loom passes near the exhaust manifold
- 4. On diesels: failed injector entirely (usually accompanied by other codes)
- 5. Less common: ECU output stage fault
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Test injector resistance against spec at the connector, typical 12-16 ohms on petrol, around 1-2 ohms on common-rail diesels
- 2. Inspect connector for damage, oil contamination, or backed-out pins
- 3. Check wiring continuity from injector to ECU
- 4. Swap test: switch cylinder 1 injector with another cylinder; if the fault follows the injector to the new cylinder, the injector is the cause
- 5. On diesels, perform a leak-off test to confirm the injector is sealing properly
Common questions about P0201
I have P0201 but no misfire code, why? +
Possible if the fault is intermittent and hasn't reached the misfire counter threshold to set P0301. The injector circuit fault appears before the misfire pattern fully develops. Address it now rather than waiting for the misfire to appear, the underlying cause is the same and prompt action prevents cat damage from unburnt fuel.
Will replacing one injector affect the others? +
On common-rail diesels, replacing one injector requires the new one to be 'coded' to the ECU, the IMA or correction values are written so the ECU knows the new injector's flow characteristics. The other injectors retain their existing codes. On petrol port injection, no coding is usually needed.
How much should a diesel injector replacement cost? +
Parts £100-£500 depending on car. Labour 1-3 hours. Specialist coding £30-£80. Total £200-£700 typically for one injector. Some workshops will recommend replacing all injectors at once if the others are also high-mileage, this is sound advice on common-rail diesels because they tend to wear together. Whole-set replacement £600-£2,000.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →