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P0208 Generic (SAE)

Injector Circuit/Open - Cylinder 8

Updated 2026-10-02 · Fuel & air metering (injector circuit)

Severity
Medium
Typical repair cost
60 – 480 EUR
System
Powertrain

What it means

The ECM has detected that the control circuit for the cylinder 8 fuel injector is open, shorted, or returning an implausible voltage. The module checks each injector by monitoring the driver pin voltage between pulses and the current rise when the driver switches on. Cylinder 8 is usually the last cylinder in the firing order on a V8 and sits at the rear of one bank, where the harness is closest to heat and often hardest to inspect.

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Symptoms

  • Check Engine light, often flashing under load when misfire follows
  • Rough idle and vibration felt through the steering wheel and seat
  • Noticeable power loss, especially when towing or climbing
  • Companion code P0308 and sometimes P0300
  • Fuel trim shift and higher consumption on the affected bank

Common causes

  1. Failed injector coil on cylinder 8 (open winding or internal short)
  2. Heat-damaged wiring at the rear of the bank near the exhaust manifold or turbo
  3. Connector terminal corrosion from water tracking along the harness into the rear of the engine
  4. Open in the shared supply wire feeding injectors 5-8 (bank fuse or relay)
  5. Injector driver failure in the ECM, sometimes caused by a shorted injector
  6. Rodent damage to the harness behind the engine

How to diagnose

  1. Confirm which physical cylinder is number 8 for this engine family and check whether P0205-P0207 are also stored; multiple codes on one bank point to the shared supply, not the injector.
  2. Unplug the injector and measure coil resistance - compare to a known good injector on the same engine; a difference of more than 1-2 ohm or an open reading means replace.
  3. Key on, measure voltage at the harness supply pin: 12 V expected. Then measure driver pin to ground with the connector plugged and engine running - should average 10-11 V because the pulse is short.
  4. Use a noid light while cranking to confirm the ECM pulses the circuit; if there is no pulse, check continuity from the ECM driver pin to the connector (under 1 ohm).
  5. Inspect the rear of the bank by hand with a mirror and inspection light for melted insulation or a connector that is loose on its lock.
  6. If the injector and wiring test good, scope the driver output at the ECM pin; a driver that never pulls low means the ECM output stage has failed.

Frequently asked questions

Why is cylinder 8 so often the one with wiring faults?

It sits at the back of the bank where the harness runs past the exhaust and is sprayed by water from the cowl; heat and moisture age the insulation faster than at the front.

Will an injector cleaner fix P0208?

No. This is an electrical circuit code, not a flow or clogging problem. Cleaner cannot repair a broken winding or corroded terminal.

Do I have to replace all eight injectors?

Not for a circuit fault. Replace the failed unit; a full set is only justified on high-mileage engines with spray-pattern problems.

Related codes

P0207P0308P0201P0300

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