Cylinder 1 Injector Circuit High
What it means
The engine computer has detected higher than expected voltage on the control circuit of the cylinder 1 fuel injector. The usual cause is a control wire touching a voltage source, or a shorted winding inside the injector that draws too much current, and the injector often stops working properly so this cylinder misfires. Cylinder 1 is present on every engine, including three-cylinder engines.
Symptoms4
- Check engine light on.
- Engine shake and rough running from weak combustion in cylinder 1.
- Loss of power, especially when climbing hills or accelerating.
- The misfire code P0301 may be stored with it.
Possible causes5
- Injector control wire touching a wire that carries battery voltage because of rubbing or melted insulation.
- Shorted internal winding in the cylinder 1 injector, giving lower resistance than specified.
- Moisture or corrosion inside the connector bridging its terminals.
- Incorrect injector type or non-original wiring from an earlier repair.
- Faulty injector driver inside the engine computer (rare).
How to diagnose5
- Read all stored codes and save the freeze frame data before clearing anything.
- Inspect the cylinder 1 injector connector and wiring for melted insulation, wires stuck together or signs of moisture.
- Measure the injector winding resistance and compare it with the manufacturer specification; very low resistance means an internal short.
- Compare its resistance with the cylinder 2 injector, or swap the two injectors if practical and see whether the code moves to the other cylinder.
- Disconnect the injector and the engine computer, then check the control wire for a short to a voltage source.
How to fix6
- Dry and clean the connector, and replace corroded terminals.
- Repair the wire touching the voltage source, re-insulate it and secure it away from heat and rubbing.
- Replace the cylinder 1 injector if its resistance is below specification.
- Fit an injector that matches the manufacturer specification if the installed one is incorrect.
- Test or replace the engine computer only if the wiring and injector are proven good.
- Clear the codes, then run the engine, road test and confirm the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
The cost stays low when the fault is a connector or wire, rises when a new injector is needed, and can go higher in the rare cases where the computer is damaged.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Is the injector always the cause of P0262?
No. A wire touching a voltage source or a wet connector is often to blame, so measure the injector resistance and check the wiring before buying a new injector.
Can the engine computer be damaged if this is left unfixed?
A short in this circuit forces extra current through the injector driver inside the computer, and leaving it for a long time can damage it, so repair it soon.
Where is cylinder 1?
On many engines cylinder 1 is at the timing belt or chain end, but numbering differs between makers, so confirm it from the manufacturer's cylinder numbering diagram before touching anything.
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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