Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. P0066 OBD-II Trouble Code: Air Assisted Injector Control Circuit or Circuit Low

P0066 OBD-II Trouble Code: Air Assisted Injector Control Circuit or Circuit Low

check engine light logo

P0066 trouble code definition

Air Assisted Injector Control Circuit or Circuit Low

What the P0066 code means

This code indicates that the powertrain control module (PCM) is detecting a voltage from the air assisted injector control circuit that is below specifications. When this low voltage is detected, the idle air/fuel mixture may not be within specifications and will therefore set off a Check Engine Light.

What causes the P0066 code?

This code can be caused by the air assisted injector control wiring or connectors having a short or being damaged in some way. If the air assisted injector control valve is unplugged or has a bad connection, that can also cause this code. There is also an injector control relay that may have gone bad that could cause this code as well.

What are the symptoms of the P0066 code?

Symptoms of this code would include the Check Engine Light being illuminated, slight stumble or hesitation from the engine when the throttle is released, or the engine may die completely in very extreme cases.

The air assisted injector system works to better atomize the fuel during deceleration of the vehicle. If the voltage to the air assisted injector system is too weak to open and close the air assisted injector control valve, the air/fuel mixture may be too rich temporarily during deceleration. This is what would cause the stumble and hesitation. The Check Engine Light comes on due to the fact that this system is connected to the powertrain control module.

How does a mechanic diagnose the P0066 code?

When diagnosing this issue, a mechanic might start with inspecting the air assisted injector system parts such as the air assisted injector valve, wiring, and vacuum hoses that are associated with this system for any faults such as shorted wiring, torn or frayed vacuum hoses, faulty injector valve, or bad electrical connections. This diagnosis would include using a digital multimeter to check voltage at specific points in the circuit to ensure they are within specification as well as a good visual inspection of all parts. Any faults that are found would be noted and repaired at the customer’s earliest convenience.

Common mistakes when diagnosing the P0066 code

Common diagnostic mistakes that could be made during the repair of this issue could include replacing the fuel injectors or the air assisted injector valve without testing their functionality. Replacing any parts without first verifying that the are faulty would be a diagnostic mistake and is also very common.

How serious is the P0066 code?

This code would not be considered very serious due to the fact that it only affects the engine under certain conditions. It would be advised to resolve the issue as soon as possible, since driving the engine under abnormal conditions for a long period of time can cause internal engine damage. The best description for the seriousness of this code would be a minor problem that can get much worse if it is ignored for a long period of time.

What repairs can fix the P0066 code?

Repairs that can fix the P0066 code would include:

Additional comments regarding the P0066 code

If any of the system wiring is damaged, the most inexpensive way to resolve the issue would be to wrap electrical tape around the damaged portion of the wire as opposed to replacing the entire air assisted injector circuit wiring harness. Also, even if the vacuum lines are not the cause of this code to be set in the powertrain control module, it is a good idea to go ahead and replace them in the process of servicing this system as a preventative maintenance service.

Need help with a P0066 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...


Related questions

Q: I drives Toyota corella S 2005 model.My check engine light is constantly on and I noiced there i

If the spark plugs have not been changed in 85K miles, then I suggest putting in new spark plugs. Also, you would need to put a fuel injection cleaner in the fuel tank to help clean out the fuel system...

Q: 1999 Nissan Altima won't stay running. I changed the thermostat.

First of all, it isn't possible to tell you exactly what is wrong with your car without direct testing, in other words, diagnosing it. If the thermostat made the car run at the proper temperature, then that is not likely...

Q: Check engine and oil light on

If your vehicle's check engine light illuminates, there is a malfunction that should be diagnosed and repaired. If you request a check engine light diagnostic, a certified mechanic from YourMechanic would use a code scanner to retrieve diagnostic trouble code(s)...