DTC P0065 – Air-Assisted Injector Control Range/Performance.

✅ What P0065 Means

Your ECM/PCM controls an air-assist system that helps atomize fuel during injection (used in some petrol engines).
P0065 sets when the ECM sees the air-assist injector control signal outside the expected range.

This usually involves:

An air-assist solenoid valve

Vacuum/air supply lines

Wiring and connectors

Sometimes carbon buildup in intake passages

🔍 Common Symptoms

Hard cold start

Rough idle

Poor fuel economy

Hesitation

MIL ON (Check Engine Light)

🔧 Possible Causes

Electrical

1. Open/short in the air-assist injector control circuit

2. Faulty air-assist injector solenoid

3. Corroded/loose connectors

4. Power or ground supply issue to the solenoid

Mechanical

5. Blocked or leaking air-assist passages

6. Ruptured or loose vacuum/air hoses

7. Carbon clogging in intake/throttle body

8. Low system air pressure (if pump-based)

ECM-related

9. ECM driver fault (rare)

🧰 Step-by-Step Diagnosis (Technician Friendly)

1. Visual Inspection

Check the air-assist solenoid connector for:

Green corrosion

Loose pins

Oil contamination

Inspect the air hoses from:

Air box/intake → solenoid → injector ports

Look for:

Cracks

Disconnected hoses

Blockage

> 60% of P0065 cases are due to hose leaks or carbon blockage.

2. Check Solenoid Power Supply

Using a multimeter:

Key ON

One pin should have battery voltage (10–14V)

If no power:

Check fuse

Check wiring from the main relay

3. Test the Solenoid Resistance

Typical resistance: 20–40 Ω (varies by model)

If open circuit → Replace solenoid

If shorted (<10 Ω) → Replace solenoid

4. Command the Solenoid with Scanner (Active Test)

Using bidirectional control:

Command ON/OFF

Listen for a clicking sound

If no click:

Solenoid failed

Or no ground signal from ECM

If it clicks but code returns → Range/performance issue (air flow or partial blockage)

5. Check Vacuum/Air Supply

Verify the injector air passages are not blocked

Clean carbon around:

Intake manifold air passages

Throttle body

Air assist ports near injectors

6. Check Wiring Continuity

Between ECM → Solenoid connector:

Should be 0–1 Ω

Repair any high resistance or damaged insulation

7. ECM Driver Test (Last Step)

Only after all above checks:

Back-probe ECM air-assist control pin

Verify duty cycle changes during command test
If ECM output is fixed or dead → ECM fault (rare)

🛠 Most Common Fixes

⭐ Replace faulty air-assist solenoid
⭐ Repair damaged wiring to solenoid
⭐ Clean clogged air assist passages
⭐ Replace cracked/loose vacuum hoses
⭐ Rare: Replace ECM

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