Diagnostic Trouble Code (DTC): P0065
P0065 trouble code definition
Air Assisted Injector Control/Performance
What the P0065 code means
What this code means is that the manifold absolute pressure sensor is not detecting a change in intake manifold vacuum when the powertrain control module tells the air assisted control valve to open.
If the manifold absolute pressure sensor does not sense this change in the vacuum, a trouble code will set off the Check Engine Light.
What causes the P0065 code?
This code is most commonly set due to a faulty air assisted injector valve or damaged wiring that is associated with this valve. It is also possible that one or more of the vacuum lines that connect to the air assisted injector valve could be clogged, preventing proper operation of this system and therefore setting a Check Engine Light.
What are the symptoms of the P0065 code?
Rough idling, engine stalling, and in very bad cases the engine dying are all symptoms of the P0065 code. The air assisted injector system works to atomize the fuel better when the throttle closes after acceleration. During heavy acceleration, more fuel is necessary to keep the engine running correctly.
When the throttle closes and deceleration begins, the rate of fuel changes. The air assisted injector system is intended to assist with this sudden change in fuel rate to keep the engine running smoothly. If this system is not performing properly, the air-fuel mixture at idle may be out of specification therefore causing one or more of the symptoms listed above.
How does a mechanic diagnose the P0065 code?
A diagnostic procedure would likely start with disconnecting the vacuum lines from the air assisted injector valve and blowing compressed air through them with a blower to verify that they are not restricted. If the vacuum lines are restricted, replace them as necessary.
If the vacuum lines are not restricted, the air assisted control valve will be checked next. The procedure involves removing the sensor from the vehicle and applying battery voltage to it. If a click sound is heard, the valve is likely good. It also helps to blow into the inlet hole of the valve while applying and removing battery voltage from the valve. The rate of airflow through the valve should be different when battery voltage is applied than when voltage is not applied.
If the valve proves to be functional, the wiring for the valve would be checked next to ensure that the valve is getting power and a good ground. If the valve is good and the vacuum lines are clear, the problem likely lies within the wiring for this system.
Common mistakes when diagnosing the P0065 code
A common mistake when diagnosing the P0065 code would be replacing the air assisted control valve without testing it. This is called a process of elimination diagnosis and can often times lead to wasted time and money.
It is very important to follow the manufacturer's diagnostic procedure for testing certain parts to make sure they are actually faulty before replacing them.
How serious is the P0065 code?
It is unlikely that any serious damage could be caused by this code as long as the problem is repaired as soon as possible.
Long term driving with this code set in the powertrain control module may damage internal engine parts. This would be due to the fact that the engine has been running incorrectly for a long period of time and could cause abnormal wear to engine parts.
What repairs can fix the P0065 code?
Replacing the air assisted control valve
Cleaning out or replacing the vacuum lines that are associated with the air assisted injection system
Repairing or replacing wiring related to the air assisted injection system
Replacing the powertrain control module which is rare but still possible
Additional comments regarding the P0065 code
If the air assisted injector valve is faulty and requires replacement, it is a good practice to go ahead and replace all vacuum lines that are associated with it as a measure of preventative maintenance.
Hoses are made of rubber and can become brittle and crack over time. It is possible that these hoses are already brittle and may crack during removal of the air assisted injector valve. Having the extra hoses on hand would prevent future headaches due to accidental damage of old vacuum hoses.
Need help with a P0065 code?
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This article originally appeared on YourMechanic.com as P0065 OBD-II Trouble Code: Air Assisted Injector Control/Performance and was authored by Andrew Quinn.