P0208

Injector Circuit Malfunction - Cylinder 8

P0208 is a generic OBD-II powertrain diagnostic trouble code: Injector Circuit Malfunction - Cylinder 8. It is logged by the engine control unit when the fuel/inj monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0208
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on, possible limp mode)
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What P0208 means

P0208 is set when the ECM/PCM detects an abnormal electrical condition on the fuel injector control circuit for cylinder 8. Like the other codes in the P0201–P0208 family, this is an electrical fault — the control module observed unexpected voltage or current on the cylinder 8 driver line. Cylinder 8 is present only on V8, V10, and V12 engines. On a typical V8 firing order, cylinder 8 sits at the rear of Bank 2, giving it one of the longer wiring harness runs from the PCM.

Because cylinder 8 is often at the tail end of the Bank 2 injector harness, it is exposed to heat from the exhaust manifold and flexing near the firewall, both of which accelerate insulation degradation over time. On many domestic V8 truck platforms, the injector harness routes under the intake manifold and is only accessible after significant disassembly, making thorough harness inspection important before deciding to replace the injector. Shared power-supply fuses and relays for the bank mean that a single failed component can affect cylinders 5, 6, 7, and 8 simultaneously — if multiple P020X codes are present, start with the common power circuit before tracing individual cylinders.

A companion code P0308 may appear if combustion on cylinder 8 is disrupted. A flashing MIL during driving signals a severe active misfire that risks rapid catalytic converter damage and requires immediate attention.

Common causes

Most-frequently reported root causes when P0208 is logged.

  • 1
    Open or shorted wiring in the cylinder 8 injector harness — heat from the exhaust manifold and flexing at the firewall are typical degradation mechanisms.
  • 2
    Corroded or loose terminals at the cylinder 8 injector connector.
  • 3
    Blown fuse or failed relay on the Bank 2 injector power supply (may simultaneously affect cylinders 5–8).
  • 4
    Internal injector solenoid coil failure — open circuit or internal short.
  • 5
    Valve-cover gasket oil leak saturating the injector connector and harness.
  • 6
    Poor PCM ground or chassis ground causing voltage reference errors on the injector driver circuit.
  • 7
    Failed PCM driver transistor for the cylinder 8 channel (uncommon but possible after a sustained harness short).

Symptoms drivers notice

MIL illuminated steadily, or flashing if a severe active misfire on cylinder 8 is present.
Rough idle with a noticeable single-cylinder stumble — cylinder 8 being at the rear of Bank 2 can make the vibration feel asymmetric.
Power loss and hesitation during acceleration, especially under load.
Possible companion code P0308 (Cylinder 8 Misfire Detected) if fuel delivery is disrupted.
Elevated fuel consumption as the ECM compensates with richer mixture on remaining cylinders.
Raw fuel or sulphur smell from the exhaust if injector is stuck partially open or if unburnt fuel reaches the catalyst.

How to diagnose P0208

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all stored codes and freeze-frame data with a scan tool; note whether P0308 or other bank-2 injector codes (P0205–P0207) are present, as multiple codes may indicate a shared power-supply fault.
  2. 2
    Check the Bank 2 injector power supply fuse and relay first if multiple P020X codes are stored — repair any common-circuit fault before tracing individual cylinders.
  3. 3
    Visually inspect the cylinder 8 injector harness from the PCM to the injector plug, focusing on runs near the exhaust manifold, under the intake manifold, and at the firewall where chafing and heat damage are most common.
  4. 4
    Disconnect the cylinder 8 injector and measure solenoid resistance — port injectors are typically 12–16 Ω; an open or near-zero reading indicates an internal injector failure.
  5. 5
    Use a noid light at the cylinder 8 injector connector during cranking to verify the PCM is outputting a switching signal; no flash means the fault is upstream in the wiring or the PCM driver.
  6. 6
    Back-probe the injector signal circuit with a multimeter or oscilloscope while the engine idles to confirm commanded pulse width and rule out an intermittent open.
  7. 7
    Swap the cylinder 8 injector with a known-good injector from another cylinder and re-scan to determine whether the fault follows the component or remains on the circuit before replacing any parts.

Related powertrain codes

Frequently asked questions

If I have P0205, P0206, P0207, and P0208 all at once, what does that mean?

Multiple injector circuit codes for an entire bank strongly suggest a shared fault — typically a blown fuse or failed relay on the Bank 2 injector power supply. Check the common power circuit before inspecting individual cylinder wiring.

How is P0208 different from P0308?

P0208 is an electrical circuit fault — the PCM detected wrong voltage on the injector driver line. P0308 is a combustion misfire — the crank sensor detected a rough-running event on cylinder 8. Both can be present together, but P0208 can appear without an active misfire if the circuit fault is intermittent.

My V8 runs fine after warm-up but sets P0208 on cold start — why?

Intermittent faults that appear only when cold often point to a connector or terminal with marginal contact that improves as the metal warms and expands, or to moisture in the connector that evaporates once the engine is hot. Inspect and clean the cylinder 8 connector and look for hairline cracks in the harness insulation near the firewall.

Can I clear P0208 and keep driving?

You can clear and monitor the code, but if it returns with a steady MIL and only mild symptoms you should arrange a repair promptly. If the MIL is flashing, stop driving — a severe misfire on cylinder 8 will overheat the catalytic converter and can cause expensive secondary damage.

Disabling P0208 in software

RaceTune can permanently disable P0208 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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