Powertrain, generic · Fuel and air metering, auxiliary emission controls

P0066 Air Assisted Injector Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Short to ground or open circuit in the control or supply wire
Solenoid coil open or high resistance
Connector corroded
Output driver in the engine control module faulty

Symptoms

  • Check engine light on
  • Unstable idle
  • Poorer cold starting

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–150
Time0.5–1 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

air assisted injector solenoidair assist hosesfuel injectors

Related codes

P0065P0067P0505

References: law.cornell.edu, patents.google.com, patents.google.com.