Failed fuel injector for cylinder 4 (open or shorted internal coil); Damaged or corroded electrical connector at the cylinder 4 injector; Broken, chafed, or shorted wire in the injector harness near the cylinder head; Faulty engine control module (ECM) injector driver for cylinder 4; Poor ground connection for the injector circuit; Aftermarket or damaged injector with incorrect resistance

DTC codes / Volkswagen codes / P1204

P1204 · VolkswagenCylinder 4 Fuel Injector Circuit Electrical Malfunction

Q: What does code P1204 mean?

Cylinder 4 Fuel Injector Circuit Electrical Malfunction. P1204 on a Volkswagen means the engine control module (ECM) has detected an electrical fault in the circuit that operates the fuel injector for cylinder 4. The ECM monitors the injector driver circuit for abnormal current draw or voltage, and this code sets when the expected electrical signature is missing or out of range.

P1204 on a Volkswagen means the engine control module (ECM) has detected an electrical fault in the circuit that operates the fuel injector for cylinder 4. The ECM monitors the injector driver circuit for abnormal current draw or voltage, and this code sets when the expected electrical signature is missing or out of range.

SystemPowertrain

Code typeVolkswagen specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Often no symptoms besides the warning light, especially if the fault is intermittent
Rough idle or misfire that is most noticeable at idle and low engine speeds
Noticeable loss of power and reduced fuel economy
Engine may stumble or hesitate under acceleration
In severe cases, the engine may run on three cylinders and shake violently
A strong raw fuel smell may be present if the injector is stuck open

Common causes, most likely first

Failed fuel injector for cylinder 4 (open or shorted internal coil)
Damaged or corroded electrical connector at the cylinder 4 injector
Broken, chafed, or shorted wire in the injector harness near the cylinder head
Faulty engine control module (ECM) injector driver for cylinder 4
Poor ground connection for the injector circuit
Aftermarket or damaged injector with incorrect resistance

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm the fault is current and not history
Inspect the cylinder 4 injector connector and harness for corrosion, chafing, or loose pins
Measure the resistance of the cylinder 4 injector and compare it to the other injectors
Check for battery voltage at the injector connector with the key on and engine off
Perform a continuity and short-to-ground test on the injector control wire from the ECM
Swap the cylinder 4 injector with a known-good injector from another cylinder and see if the code moves
If the circuit and injector test good, diagnose the ECM driver circuit or replace the ECM as a last resort

What the P1204 code does not always mean

A P1204 does not automatically mean the injector itself has failed; a chafed wire in the harness near the cylinder head is a very common cause that is often missed.
Volkswagen injector circuits are often batch-fired or sequential, and a fault in the shared power or ground circuit can set this code even when the cylinder 4 injector is fine.
An intermittent connector fault can set P1204 only when the engine is hot or vibrating, so a cold static test may pass and mislead you.
After replacing an injector, the ECM may need adaptation or the code may remain stored until several drive cycles complete.
A stuck-open injector can hydrolock the cylinder and cause catastrophic engine damage, so raw fuel smell with this code demands immediate attention.

Can I keep driving with P1204?

It is not safe to continue driving with an active P1204 because a misfiring or stuck-open injector can damage the catalytic converter and, in worst cases, the engine. If the engine is running rough or you smell raw fuel, stop driving and have the vehicle towed to a repair shop.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Volkswagen vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.