P0067
Air Assisted Injector Control Circuit HighP0067 is a generic OBD-II powertrain diagnostic trouble code: Air Assisted Injector Control Circuit High. 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.
What P0067 means
Code P0067 is logged by the powertrain control module (PCM) when it detects a higher-than-expected voltage in the air assisted injector control circuit. The air assisted injection system helps cold-start emissions control by routing metered air to fuel injectors during warm-up, and is managed by a PCM-driven solenoid valve. The PCM monitors circuit voltage against a defined high threshold; when the measured voltage exceeds this limit — typically approaching or equalling battery voltage on a circuit the PCM expects to pull low — P0067 is set. This high-voltage condition most commonly points to a short to the battery positive supply in the control wiring, a failed PCM driver that cannot properly pull the circuit to ground, or an open in the ground/return path that causes the circuit to float high. As with P0066, this is a hard electrical fault distinct from the performance-based P0065. The system is most active on cold starts below approximately 160°F coolant temperature, so the fault may be most apparent after an overnight cold soak. Drivability at full operating temperature is typically unaffected, but the stored MIL will prevent the vehicle from passing an OBD-II visual inspection, and persistent operation without repair can degrade cold-start catalyst efficiency over time.
Common causes
Most-frequently reported root causes when P0067 is logged.
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1
Short to battery positive voltage in the solenoid control wire, allowing supply voltage to appear on the monitored circuit continuously
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2
Open circuit in the ground/return path of the solenoid, causing the circuit to float at high voltage
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3
Failed PCM low-side driver that cannot switch the solenoid circuit to ground when commanded
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4
Damaged or melted wiring harness with a control wire shorted to a nearby battery-positive wire
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5
Faulty air assisted injector solenoid with an internal open on the ground side
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6
Corroded ground connection at the solenoid body or chassis ground splice point
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7
Aftermarket accessory wiring inadvertently creating a back-feed onto the control circuit
Symptoms drivers notice
How to diagnose P0067
A typical diagnostic flow when this code is present.
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1
Inspect the solenoid connector and nearby wiring for insulation damage or contact with battery-positive wires
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2
With the ignition on and the solenoid circuit commanded active by the PCM, measure voltage at the solenoid connector; a reading at or near battery voltage when the PCM is attempting to pull low suggests a short to power
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3
Measure the solenoid resistance — an open reading (infinite resistance) on the ground-side coil winding indicates an internal solenoid fault causing the circuit to float high
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4
Check the solenoid chassis ground connection; a high-resistance or missing ground can cause the control circuit to sit at high voltage
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5
Backprobe the PCM connector for the solenoid output pin and verify the PCM is correctly switching to ground — a pin that stays high-side indicates a failed PCM driver
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6
Repair any identified wiring shorts, replace solenoid if resistance is out of spec, and clear codes before cold-soak re-test
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7
If no wiring or solenoid fault is found, consult manufacturer TSBs for PCM software or hardware issues on the specific platform
Related powertrain codes
- P0065 — Air Assisted Injector Control Range/Performance
- P0066 — Air Assisted Injector Control Circuit or Circuit Low
- P0087 — Fuel Rail/System Pressure - Too Low
- P0088 — Fuel Rail/System Pressure - Too High
- P0089 — Fuel Pressure Regulator 1 Performance
- P0090 — Fuel Pressure Regulator 1 Control Circuit
Frequently asked questions
What is the difference between P0066 and P0067?
P0066 indicates the circuit voltage is too low (short to ground or open supply), while P0067 indicates the circuit voltage is too high (short to power or open ground/return). Both are hard circuit faults as opposed to P0065, which is a performance-based fault.
Can the PCM itself cause P0067?
Yes. If the PCM's internal low-side transistor driver for the solenoid circuit fails open, it cannot pull the circuit to ground, leaving the monitored voltage high and setting P0067. However, PCM failure is relatively rare and should only be suspected after all wiring and solenoid checks are exhausted.
Will P0067 prevent the vehicle from starting?
No. The air assist system is a supplemental cold-start emissions device and is not required for engine starting or operation. The vehicle will start and run normally, though cold-start emissions performance will be degraded.
How do I confirm the short to power causing P0067?
Disconnect the solenoid connector and measure the voltage on the PCM-side control wire with the ignition on. If battery voltage is present on this wire with the connector unplugged and the PCM not commanding the circuit, you have confirmed a short to power in the harness upstream of the solenoid.
Disabling P0067 in software
RaceTune can permanently disable P0067 — 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.
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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