P0066 code meaning
Air Assisted Injector Control Circuit Low
Powertrain system Generic code P00xx codes Check engine light
What P0066 means
Air-assisted injectors have an air sleeve around the nozzle tip: air flowing past at high speed breaks the fuel spray into finer droplets, which improves combustion and cold starts and lowers hydrocarbon emissions. On port-injected engines this air is taken upstream of the throttle and dosed by a pulse-width modulated bypass solenoid; because it bypasses the throttle, it is part of the idle air. The system is rare and mainly found on older engines. P0066 reports too low a voltage in the control circuit of the air-assist solenoid, typically a short to ground or, depending on the circuit, an open circuit.
P0066 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 1 hours
- Clears after repairAfter a drive cycle
Symptoms of P0066
- Check engine light on
- Unstable idle
- Poorer cold starting
Common causes of P0066
- Most likelyShort to ground or open circuit in the control or supply wire
- Most likelySolenoid coil open or high resistance
- PossibleConnector corroded
- Less likelyOutput driver in the engine control module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Air assisted injector solenoidAir assist hosesFuel injectors
What each part of P0066 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| 66 | The exact fault in that area. |
What to do next
- Note P0066 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0066
What does P0066 mean?
P0066 means "Air Assisted Injector Control Circuit Low". Air-assisted injectors have an air sleeve around the nozzle tip: air flowing past at high speed breaks the fuel spray into finer droplets, which improves combustion and cold starts and lowers hydrocarbon emissions. It is a generic code, so it means the same on every make.
Is it safe to drive with P0066?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0066 fail an emissions test?
Yes, it can. P0066 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0066 to fix?
Difficulty: medium. A typical repair takes 0.5 to 1 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0066 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.