Code Definition

P0066 — Air Assisted Injector Control Circuit or Circuit Low

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0066

P0066 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0066 is stored, the module has detected a signal or supply voltage lower than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0066 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The P0066 code indicates an issue with the air assisted injector control circuit, specifically pointing to a low voltage condition in the circuit. Air assisted injectors enhance the fuel-air mix within the engine, particularly under certain operating conditions such as cold starts. The Engine Control Module (ECM) sets this code when it detects that the voltage in the control circuit for the air assisted injector system is lower than expected, which could affect the system's functionality and thereby impact engine performance and emissions.

Quick Facts