Technical Description of OBD-II Trouble Code
The circuit controlling the air assisted injector is either malfunctioning or has a low electrical value.
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to OBD-II equipped vehicles with an air assisted fuel injector. This code can be found in various vehicle brands such as Subaru, Jaguar, Chevy, Dodge, VW, Toyota, Honda, etc., but it is most commonly seen in Subaru and Jaguar vehicles. The specific repair steps may vary depending on the make, model, and engine of the vehicle.
The air assisted injector functions similarly to a normal fuel injector. As the name suggests, it uses air to help atomize the fuel during injection. This injector is typically used to aid in cold starts, as a richer air/fuel mixture is required to start a cold engine.
The atomization process that occurs when air is introduced to a normal injector is important because it ensures a more evenly distributed spray. This is crucial because these systems usually have only one injector mounted to the throttle body or intake, and the atomized fuel spray needs to be distributed among multiple cylinders.
The engine control module (ECM) triggers the check engine light and displays the P0066 code when it detects a condition outside the specified range within the circuit of the air assisted injector. This condition is typically related to an electrical issue, but it can also be caused by an internal malfunction within the injector itself.
The P0066 code indicates a low electrical value within the circuit of the air assisted injector. This code is closely related to the P0065 and P0067 codes.
What is the severity of this DTC?
The severity of this code is considered moderate to low. It does not significantly affect the overall performance of the engine at normal operating temperature. However, it should still be addressed to prevent potential damage from consistent cold starts with a lean mixture.
What are some of the symptoms of the code?
Some symptoms of the P0066 engine code may include:
What are some of the common causes of the code?
The causes of this code may include:
What are some troubleshooting steps?
It is recommended to check for any technical service bulletins (TSBs) related to your specific vehicle. Accessing a known fix from a TSB can save time and money during the diagnosis process.
Tools
When working with electrical systems, it is advisable to have the following basic tools:
Safety Tips
Basic Step #1
Refer to the service manual to locate the injector on your specific make and model. In most cases, the injector is mounted to the throttle body. Check for any vacuum leaks or damaged gaskets around the injector, as these can cause it to operate outside the desired range. Listen for any abnormal whistle noises around the vacuum hoses while the engine is running. If you have a vacuum gauge, monitor the vacuum within the intake system and compare it to the desired value.
NOTE: Replace any cracked vacuum hoses to prevent future issues.
Basic Step #2
Test the injector by measuring the resistance between the electrical pins using a multimeter. Refer to the service manual for the specific electrical values required for your make and model.
NOTE: Always use appropriate multimeter lead connectors to avoid bending pins and causing intermittent problems.
Basic Tip #3
Inspect the electrical connector on the injector for corrosion or defects. Repair or replace it as necessary. Pay attention to the routing of the harness, as it may be exposed to tight areas where chafing can occur. Ensure that the harness and wires are in good condition and properly secured.
NOTE: Disconnect the battery before performing any electrical repairs.
Basic Step #4
Test the injector circuit by disconnecting the connector on the injector and the other end at the ECM, if possible. Check for continuity in the wires within the circuit using a multimeter. You can also perform a voltage drop test to assess the integrity of the wire.
Basic Step #5
If your scan tool allows it, monitor the operation of the air assisted injector while the vehicle is running. Compare the actual values to the desired values to help determine the issue.
