P0204

Injector Circuit Malfunction - Cylinder 4

Car Fault Codes Fuel & air

Can you still drive? With care, short trips only

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 3 hours

Typical cost SAR 100 to 1,500

What it means

The engine computer has detected an open or short in the fuel injector circuit for cylinder 4. On a four-cylinder engine this means a quarter of the engine may not be getting fuel, which causes clear shaking and poor performance.

Symptoms4

Check engine light on, possibly with code P0304.
Clear engine shaking and a rough idle.
Loss of power and slow acceleration.
Occasional slightly hard starting.

Possible causes5

Corroded or poorly seated cylinder 4 injector connector.
Open or shorted wire in the cylinder 4 injector harness.
Open or shorted internal coil in the cylinder 4 injector.
Problem with injector power from a fuse or relay.
Failed cylinder 4 injector driver inside the engine computer (rare).

How to diagnose6

Inspect the cylinder 4 injector connector and confirm its terminals and lock are intact.
Measure the cylinder 4 injector resistance and compare it with the specification and with the other injectors.
Check supply voltage and continuity of the drive wire between injector 4 and the computer.
Check the drive pulses at injector 4 with a noid light or an oscilloscope.
On port-injection engines, swap the cylinder 4 injector with the one in cylinder 3; if the code moves to P0203, the injector is faulty.
Avoid ordinary test lights on direct-injection and diesel circuits, because they use high voltage.

How to fix6

Clean or replace the cylinder 4 injector connector and secure it well.
Repair the damaged wire in the cylinder 4 injector harness.
Replace a failed fuse or relay.
Replace the cylinder 4 injector if it is proven faulty.
Test or replace the engine computer only after ruling out other causes.
Clear the codes, then road test and confirm the code does not return.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a connector or wire repair and rises for an injector replacement depending on the injection system; a computer failure remains a rare, much more expensive possibility.

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 cylinder 4 the last one in the engine?

On inline four-cylinder engines it is usually at the opposite end from cylinder 1, but numbering differs between manufacturers, so check the service information before removing any injector.

Will the code go away by itself?

It may disappear for a while if a loose connector moves with vibration, but it will return unless the connector or wire is repaired.

Can I drive with this code?

Only a short distance and gently, because incomplete combustion in cylinder 4 can damage the catalytic converter.

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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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