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P0067 Code Explained: Air Assisted Injector Control Circuit High Causes, Symptoms & Fixes

P0067 code displayed on an OBD-II scanner with an air-assisted injector control solenoid and open high-voltage circuit highlighted near the intake manifold.

If your OBD-II scanner displays P0067, your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a higher-than-expected voltage condition in the air-assisted injector control circuit.

The generic SAE description for P0067 is:

Air Assisted Injector Control Circuit High

Depending on the vehicle manufacturer or scan tool, the description may appear as:

An air-assisted injector system directs controlled airflow around the fuel injector nozzle or into the intake port. This additional air helps break the injected fuel into smaller droplets, improving fuel atomization during cold starts, idle, warm-up, and low-speed operation.

P0067 is stored when the PCM detects a voltage signal above the calibrated threshold in the air-assist injector control circuit. This is commonly associated with an open circuit, broken wire, disconnected connector, failed solenoid coil, loss of ground control, or a short to voltage.

Common causes include:

P0067 may produce rough cold starts, unstable idle, hesitation, reduced fuel economy, increased emissions, or decreased engine performance. Some vehicles may show no obvious symptoms beyond the Check Engine Light.

For additional diagnostic information, visit:

P0067 Quick Facts

ItemInformation
OBD-II CodeP0067
DescriptionAir Assisted Injector Control Circuit High
CategoryPowertrain
SystemFuel and Air Metering
Main ComponentAir-Assist Injector Control Valve or Solenoid
Fault TypeHigh Voltage or Insufficient Current
SeverityModerate
Safe to Drive?Usually, with caution
Typical Repair Cost$75–900

What Does P0067 Mean?

P0067 means the PCM has measured voltage above the expected range in the circuit controlling the air-assisted injector system.

On many vehicles, the air-assist solenoid receives battery voltage on one side of its circuit. The PCM controls the solenoid by switching the opposite side to ground.

When the circuit operates normally:

  1. The PCM commands the air-assist system on.
  2. Current flows through the solenoid coil.
  3. The control valve opens or changes position.
  4. Air passes through dedicated hoses or intake passages.
  5. The PCM observes the expected electrical and engine response.

A circuit-high condition may occur when current cannot flow normally.

Possible reasons include:

In these situations, voltage can remain higher than expected because the electrical path through the solenoid is incomplete.

What Is an Air-Assisted Injector System?

An air-assisted injector system introduces additional air near the fuel injector tip or intake port.

The system is designed to improve the way fuel mixes with the incoming air before entering the combustion chamber.

Depending on the application, it may use:

The extra airflow helps break the injector spray into smaller droplets.

Improved fuel atomization can provide:

Air-assisted injection is not used on every vehicle, which is why P0067 is considerably less common than most fuel-injection codes.

Air-Assisted Injection vs Secondary Air Injection

Air-assisted injection and secondary air injection are not the same system.

Air-Assisted Injection

Air is introduced:

Its main purpose is to improve fuel atomization.

Secondary Air Injection

Air is introduced:

Its main purpose is to help burn remaining exhaust hydrocarbons and warm the catalytic converter.

Confusing the two systems can lead to testing the wrong pump, valve, hoses, and wiring.

P0067 refers to the air-assisted injector control circuit, not the conventional secondary air-injection pump system.

Why Is Additional Air Added to the Fuel Spray?

Liquid fuel must be broken into a fine mist before it can burn efficiently.

During a cold start:

The air-assisted system helps separate the fuel into smaller droplets before it reaches the combustion chamber.

Once the engine reaches normal operating temperature, fuel vaporization improves naturally. The PCM may then reduce or discontinue air-assist operation.

How the Air-Assisted Injector Circuit Works

A typical air-assist control circuit includes:

On many systems, the solenoid receives battery voltage whenever the ignition is on or the engine is running.

The PCM operates the valve by controlling the ground side of the circuit through an internal transistor.

The PCM may monitor:

If the measured voltage remains above the programmed limit, P0067 may be stored.

What Does “Circuit High” Mean?

“Circuit high” generally means the PCM detects more voltage than expected on the monitored control circuit.

This does not necessarily mean the alternator is overcharging the entire vehicle.

Instead, it means the voltage at the specific PCM input or control circuit is too high relative to the commanded operating condition.

Common circuit-high conditions include:

When the PCM commands the valve on, it expects current to flow and circuit voltage to change.

If the electrical path is open, voltage may remain high because the circuit is not being pulled toward ground as expected.

P0065 vs P0066 vs P0067

CodeDescription
P0065Air Assisted Injector Control Range/Performance
P0066Air Assisted Injector Control Circuit or Circuit Low
P0067Air Assisted Injector Control Circuit High

Generally:

The exact diagnostic logic can vary between manufacturers.

How the PCM Detects P0067

The PCM may test the air-assisted injector system during:

The PCM compares its commanded valve operation with actual circuit voltage and system response.

P0067 may be stored when:

Depending on the manufacturer, the Check Engine Light may illuminate after one failure or after the fault occurs during multiple drive cycles.

Symptoms of P0067

Possible P0067 symptoms include:

Some vehicles may run normally once the engine is warm.

Symptoms are often most noticeable:

If the circuit is open but the valve remains in a neutral position, the driver may notice little more than the Check Engine Light.

Common Causes of P0067

1. Open Air-Assist Solenoid Coil

The electrical coil inside the control solenoid may burn open.

An open coil prevents current from flowing through the component.

Common test results include:

This is one of the most direct causes of the code.

2. Broken Control Wire

A wire between the air-assist solenoid and PCM may break because of:

The insulation may appear intact even when the conductor is broken internally.

3. Disconnected Electrical Connector

A loose or disconnected connector creates an open circuit.

Inspect for:

This is especially common after intake, fuel-rail, or throttle-body repairs.

4. Control Wire Shorted to Voltage

The PCM control wire may contact:

This can keep circuit voltage high regardless of PCM command.

5. Corroded Connector Terminals

Corrosion creates resistance and can eventually interrupt current flow.

Look for:

A connector may look attached while still failing electrically under load.

6. High-Resistance Electrical Connection

Excessive resistance may develop in:

High resistance reduces current flow and may leave circuit voltage above the expected threshold.

7. Failed Air-Assist Control Solenoid

The solenoid can fail electrically or mechanically.

Possible failures include:

A mechanically stuck valve may also create system-performance symptoms even when the electrical circuit appears normal.

8. Blown Fuse

A blown fuse may remove power from the air-assist solenoid.

Depending on the circuit design and PCM monitoring strategy, this can create a circuit-high, open-circuit, or general control fault.

If the fuse is blown, inspect for:

Do not repeatedly install new fuses without identifying why the original fuse failed.

9. Failed Relay or Power Feed

Some systems use a relay to supply voltage to the air-assist solenoid.

A failed relay can cause:

Inspect the relay terminals for heat and corrosion.

10. Incorrect Replacement Component

An incorrect solenoid or valve may have:

A component that physically connects is not automatically electrically compatible.

11. Poor Previous Wiring Repair

Improper repairs may include:

Repairs in the engine compartment must tolerate heat, vibration, oil, water, and chemical exposure.

12. Damaged PCM Driver

The PCM’s internal transistorized driver may fail to complete the ground circuit.

Possible signs include:

PCM failure is uncommon and should only be considered after every external part of the circuit has been tested.

Is P0067 Serious?

P0067 is generally considered a moderate-severity diagnostic trouble code.

The vehicle may continue running, but the fault can affect:

Some sources classify P0067 as moderate to low in severity because normal warm-engine performance may be largely unaffected. However, the code should still be diagnosed rather than ignored.

The code becomes more urgent if the vehicle:

Can You Drive With P0067?

You can usually drive with P0067 for a short period if the vehicle starts, idles, and accelerates normally.

However, continued driving may result in:

Avoid driving if:

A flashing Check Engine Light can indicate active misfire severe enough to damage the catalytic converter.

How to Diagnose P0067

Step 1: Scan for Additional Trouble Codes

Check for related codes involving:

Record freeze-frame data before clearing the codes.

Important values include:

Freeze-frame data may show whether P0067 occurred during a cold start, idle, or engine warm-up.

Step 2: Confirm the Vehicle Uses Air-Assisted Injection

P0067 is uncommon.

Before ordering parts, confirm that the vehicle has:

Consult manufacturer service information and the correct wiring diagram.

Do not confuse the air-assisted injector valve with:

Several valves may live in the same neighborhood while performing entirely different jobs.

Step 3: Locate the Control Solenoid

The air-assist solenoid or valve may be mounted near the:

Trace both the wiring and hoses before disconnecting the component.

Take a photograph of the hose routing before removal.

Step 4: Perform a Visual Inspection

Inspect the complete circuit for:

Pay close attention to areas where the harness bends or passes across metal brackets.

Step 5: Inspect the Connector

Disconnect the air-assist solenoid connector.

Inspect both sides for:

Use a terminal-tension test when service information permits.

A terminal that barely touches its mating pin may pass a visual inspection and still fail under load.

Step 6: Check the Battery and Charging System

Measure battery voltage:

Inspect:

Although P0067 concerns one specific circuit, unstable system voltage can complicate diagnosis.

Step 7: Check the Fuse and Relay

Identify the fuse and relay supplying the air-assist system.

Verify:

A fuse can look intact while failing at its terminals, so voltage testing is preferable to visual inspection alone.

Step 8: Verify Power at the Solenoid

Turn the ignition on or command the circuit active with a scan tool.

Check for the specified voltage at the solenoid power terminal.

If voltage is missing, inspect:

If proper power is available, continue testing the control side.

Step 9: Measure Solenoid Resistance

Disconnect the solenoid and measure resistance across its terminals.

Possible readings include:

Always compare the measurement with manufacturer specifications.

Do not substitute a generic resistance range when exact service data is available.

Step 10: Check the Control Wire for an Open

Disconnect the solenoid and PCM connectors according to the manufacturer’s procedure.

Measure continuity through the control wire.

Look for:

Move the harness gently while monitoring resistance to identify intermittent faults.

Step 11: Test for a Short to Voltage

With both ends of the control circuit disconnected, check whether the control wire has unintended voltage or continuity to a power circuit.

A short to voltage may be caused by:

Repair the harness before replacing the solenoid or PCM.

Step 12: Perform a Voltage-Drop Test

Test the circuit under load.

Measure voltage drop across:

Excessive voltage drop can reveal resistance that a continuity test misses.

A wire can technically remain connected while being too damaged to carry enough current.

Step 13: Command the Solenoid With a Scan Tool

Use bidirectional controls, when available, to command the air-assist solenoid on and off.

Monitor:

If circuit voltage remains high when the solenoid is commanded on, suspect:

Step 14: Check Mechanical Valve Operation

Electrical operation does not guarantee proper airflow.

Inspect the valve for:

The solenoid may click while the valve remains stuck.

Clicking confirms noise production—not successful airflow management.

Step 15: Inspect Air and Vacuum Hoses

Check all related hoses for:

Although P0067 is primarily an electrical code, hose and valve problems may produce accompanying performance codes.

Step 16: Test the PCM Control Command

Only test PCM terminals using the manufacturer’s approved procedure.

Confirm:

Do not apply battery voltage or direct ground to a PCM terminal unless the service procedure specifically requires it.

Incorrect testing can damage the module.

Step 17: Repair or Replace the Failed Component

Depending on test results, repairs may include:

Use OEM or high-quality direct-fit components.

Step 18: Verify the Repair

After completing repairs:

  1. Clear all diagnostic trouble codes.
  2. Allow the engine to cool fully.
  3. Perform a cold start.
  4. Monitor air-assist circuit voltage.
  5. Confirm proper solenoid current.
  6. Observe idle quality and fuel trims.
  7. Complete the manufacturer’s drive cycle.
  8. Confirm the readiness monitors complete.
  9. Verify P0067 does not return.

Because the system may operate primarily during cold starts, final verification may require the engine to remain off long enough to cool completely.

Common Repairs and Costs

RepairEstimated Cost
Connector reconnection or minor repair$50–150
Fuse replacement$10–50
Relay replacement$50–225
Wiring repair$100–450
Connector replacement$75–275
Air or vacuum hose replacement$50–200
Air-assist solenoid replacement$150–500
Air-control valve replacement$200–700
Intake passage cleaning$150–600
PCM circuit diagnosis$150–500
PCM replacement$1,000–2,500+

Repair costs vary according to:

A disconnected connector may cost almost nothing to correct. Finding one broken wire buried beneath the intake manifold may not share that same sense of generosity.

Common Diagnostic Mistakes

Avoid these common P0067 diagnostic mistakes:

The word “injector” tends to attract the parts cannon. P0067 usually requires a wiring diagram and multimeter before it requires a shopping cart.

Vehicles Commonly Affected

P0067 is relatively uncommon because most modern vehicles do not use an air-assisted injector control system.

It may appear on certain:

Exact applications depend on:

Always verify the manufacturer’s system description before replacing components.

How to Prevent P0067

Reduce the likelihood of P0067 by:

Frequently Asked Questions

What does P0067 mean?

P0067 means the PCM has detected voltage above the expected range in the air-assisted injector control circuit.

What is an air-assisted injector?

An air-assisted injector system directs controlled airflow around the fuel injector spray or into the intake port to improve fuel atomization.

Is P0067 serious?

P0067 is usually moderately serious.

The vehicle may continue running, but cold-start performance, emissions, idle quality, and fuel economy may be affected.

Can I drive with P0067?

Usually, yes, for a limited period if the engine runs normally.

Avoid driving if the vehicle stalls, misfires severely, smells strongly of fuel, or has overheated wiring.

What commonly causes P0067?

Common causes include:

Will replacing the fuel injectors fix P0067?

Usually not.

P0067 generally concerns the air-assist control valve, solenoid, or electrical circuit—not the conventional fuel injectors.

Can a disconnected connector cause P0067?

Yes.

A disconnected solenoid creates an open circuit, which may cause the PCM to detect higher-than-expected control-circuit voltage.

Can a broken wire cause P0067?

Yes.

An open power or control wire can prevent current from flowing through the air-assist solenoid.

Can a blown fuse cause P0067?

Possibly.

A blown fuse may interrupt circuit power and trigger a high, open, or general control-circuit fault depending on the vehicle’s diagnostic strategy.

What is the difference between P0065 and P0067?

P0065 indicates the air-assisted injector system is not performing within the expected range.

P0067 indicates that control-circuit voltage is too high.

What is the difference between P0066 and P0067?

P0066 usually indicates low voltage, excessive current, or a short to ground.

P0067 indicates high voltage, insufficient current, or an open circuit.

Can P0067 cause rough idle?

Yes.

The engine may idle roughly, especially during cold starts when the air-assist system is most useful.

Can P0067 reduce fuel economy?

Yes.

Poor fuel atomization and incorrect cold-start combustion may increase fuel consumption.

Can P0067 cause an emissions failure?

Yes.

An active Check Engine Light or incomplete readiness monitors may cause the vehicle to fail an emissions inspection.

How much does it cost to fix P0067?

Repairs may cost as little as $50 for a minor connector issue or several hundred dollars for wiring, valve, or solenoid replacement.

PCM replacement can exceed $1,000 but is rarely required.

Final Thoughts

The P0067 code means the PCM has detected a high-voltage condition in the air-assisted injector control circuit.

The most common causes include an open solenoid coil, broken control wire, disconnected connector, short to voltage, corroded terminals, or a failed air-assist control valve.

Begin by confirming that the vehicle actually uses an air-assisted injector system. Next, inspect the connector and harness, verify circuit power, measure solenoid resistance, check the control wire for an open or short to voltage, and command the system with a capable scan tool.

Do not replace ordinary fuel injectors simply because the trouble-code description contains the word “injector.” The fault usually belongs to the airflow-control circuit surrounding the injectors. A wiring diagram and multimeter remain considerably cheaper than replacing unrelated parts until the Check Engine Light becomes bored and leaves.

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