OBD-II Code · Fuel & Air
P0285
Cylinder 9 Injector Circuit Low
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$55–$980
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
V10-only · cyl 9 injector shorted.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Misfire cyl 9
- Check engine light
Likely causes
- Shorted injectorMost common
- Spark plug blowout collateral
Read the full diagnostic procedureP0285 indicates a low-voltage / short condition on the cylinder 9 injector circuit, which only appears on V10 and V12 engines.
P0285 indicates a low-voltage / short condition on the cylinder 9 injector circuit, which only appears on V10 and V12 engines.
Cheapest first
- swap injector 9 with a known-good neighbor and recheck;
- PFI windings should ohm 11 to 17, and on V10s like the Ford 6.8L Triton this is a port-injected saturated solenoid, so under-10-ohm readings indicate a shorted coil.
- With the injector unplugged and key on, the driver pin should be open to ground; any continuity to chassis indicates a harness short to ground.
- Pulse width on a warm-idle Ford 6.8L is typically 3 to 4 ms; on a BMW S85 V10 the GDI-like sequential setup runs 2 to 3 ms at idle.
- Caveat: the Ford 6.8L 2V/3V Triton has spark-plug-blowout history on cylinder 9 because that head is shared with the 5.4L V8 pattern; a blown plug can damage the injector harness running alongside the COP, so always inspect for plug-thread damage signatures before condemning electrical parts.
Vehicle-specific patterns1997 to 2010 Ford E-Series and Super Duty 6.8L V10 Triton is the dominant population for this code and most failures trace to harness chafe at the ri…
- 1997to 2010 Ford E-Series and Super Duty 6.8L V10 Triton is the dominant population for this code and most failures trace to harness chafe at the right-rear valve cover or to spark-plug-blowout collateral damage on cylinder 9;
- 2006to 2010 BMW M5/M6 S85 V10 has documented bank-2 injector driver weakness in the DME;
- 2003to 2010 Dodge Viper 8.3L V10 has cracked injector connectors from underhood heat.
Estimated repair$55 to $980.
Look up another code
P0285 — frequently asked
What does a P0285 code mean?
V10-only · cyl 9 injector shorted.
What causes a P0285 code?
Common causes: Shorted injector; Spark plug blowout collateral.
What are the symptoms of a P0285 code?
Typical symptoms: Misfire cyl 9; Check engine light.
Is it safe to drive with a P0285 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $55-$980.
How do I diagnose a P0285 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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