P0066
UniversalP0066 Air Assisted Injector Control Circuit/Open - Circuit Low
Medium SeverityThis code indicates a low voltage condition or an open circuit within the control circuit for the air assisted fuel injector. This can lead to improper fuel atomization, potentially affecting engine performance and fuel economy as the engine's fuel delivery system is compromised.
⚠️ Before You Begin (Safety First)
Always wear appropriate personal protective equipment, such as safety glasses and gloves, when working on your vehicle. Before performing any repairs, ensure the engine is off and cool. Disconnect the battery's negative terminal to prevent accidental electrical shorts and unintended engine operation.
Common Symptoms
- Check Engine Light illuminated
- Reduced engine power or performance
- Rough idle or engine misfires
- Poor fuel economy
- Increased exhaust emissions
- Hesitation or stumbling during acceleration
Common Causes
- Faulty or failed air assisted injector
- Open circuit in the wiring to the air assisted injector
- Short to ground in the wiring to the air assisted injector
- Corroded or loose electrical connections at the injector or harness
- Faulty Powertrain Control Module (PCM) (rare)
Frequently reported on: Honda CR-V (2007-2011), Toyota Corolla (2009-2013), Ford Focus (2012-2018), General/Universal (for vehicles with air assisted injectors)
Diagnostic Steps
- Visually inspect the wiring harness and electrical connector for the air assisted injector for any signs of damage, fraying, corrosion, or loose connections. Repair or replace any damaged components.
- Using a multimeter, test for proper voltage and continuity at the air assisted injector connector according to your vehicle's service manual specifications.
- Measure the resistance of the air assisted injector itself using a multimeter. Compare the reading to the manufacturer's specified range; replace the injector if it is out of specification.
- If all electrical checks are within spec and the injector is sound, clear the Diagnostic Trouble Code (DTC) using an OBD-II scanner and test drive the vehicle to verify if the code returns.
👨🔧 When to Call a Professional
If you have thoroughly inspected and tested the wiring, connectors, and replaced the air assisted injector, and the P0066 code persists, it is advisable to seek professional diagnostic assistance. A complex electrical issue or a Powertrain Control Module (PCM) fault may be present.
Commonly Asked Questions
What does P0066 mean?
P0066 indicates an issue with the control circuit for your engine's air assisted fuel injector, specifically a low voltage or open circuit condition, which impacts fuel atomization.
Is it safe to drive with a P0066 code?
While you might be able to drive, it's not recommended for extended periods. It can lead to poor engine performance, reduced fuel economy, increased emissions, and potentially cause further engine damage over time if not addressed.
How much does it cost to fix P0066?
Repair costs vary. A simple wiring repair might be inexpensive, while replacing the air assisted injector itself could range from $100 to $300+ for parts, plus labor, depending on your vehicle.
Can I replace the air assisted injector myself?
Yes, with basic tools and some mechanical knowledge, replacing an air assisted injector is a manageable DIY task for many. However, proper diagnosis of the circuit fault is crucial before replacement.
Could a P0066 code be caused by a bad PCM?
A faulty Powertrain Control Module (PCM) is a very rare cause for P0066. It should only be considered after all other potential issues, such as wiring, connectors, and the injector itself, have been thoroughly diagnosed and ruled out.