P0068 trouble code definition
Manifold Absolute Pressure or Mass Air Flow Sensor Throttle Position Correlation
What the P0068 code means
This code means that the manifold absolute pressure or mass air flow sensors that detect air flow through the air induction system and the intake manifold have readings that contradict the readings that are coming from the throttle position sensor. The throttle position sensor communicates to the powertrain control module how far open the butterfly valve is within the throttle body, and therefore the amount of air that should be introduced into the intake manifold.
What causes the P0068 code?
Possible causes of the P0068 code would include:
- A faulty mass air flow sensor or the wiring that is associated with it
- A faulty manifold absolute pressure sensor or the wiring that is associated with it
- A vacuum leak on the intake manifold, air induction system, or throttle body
- A loose or damaged electrical connection related to this system
- A faulty or improperly installed throttle position sensor or the wiring that is associated with it
What are the symptoms of the P0068 code?
Some symptoms of the P0068 code that the driver may experience could include a rough engine idle during parked and deceleration conditions, a loss of power due to excess air that could be introduced into the system that could be affecting the air/fuel ratio, and of course the Check Engine Light.
How does a mechanic diagnose the P0068 code?
A mechanic would diagnose the P0068 code by inspecting and testing the manifold absolute pressure sensor, the mass air flow sensor, the throttle position sensor, the intake manifold, and the air induction system. As for the sensors, the mechanic would check to verify that all sensors are properly installed and tested for proper functionality. A mechanic would also check the engine for vacuum leaks in the intake manifold, throttle body, and air induction system via vacuum gauge and/or a smoke test.
Common mistakes when diagnosing the P0068 code
Common mistakes when diagnosing the P0068 code could include replacing fuel or ignition system parts by assuming the issue is a misfire, as this can make the engine run similarly. Another mistake when diagnosing this issue could include replacing one or more sensors without testing their functionality prior to the replacement. It is very important to verify all faults before attempting to make any repairs.
How serious is the P0068 code?
The P0068 code may not be serious at first, but could lead to the car having more serious conditions. The engine will likely run rough until the issue is resolved. If the engine is running rough for an extended period of time, engine damage may result. It would be advised to have this issue diagnosed and repaired as soon as possible in order to prevent further damage to the engine.
What repairs can fix the P0068 code?
Repairs that can fix the P0068 code would include:
- Adjusting the mounting or installation of the mass air flow sensor, manifold absolute pressure sensor, or throttle position sensor
- Replacing the mass air flow sensor
- Replacing the manifold absolute pressure sensor
- Repairing or replacing wiring that is associated with these two sensors
- Repairing a vacuum leak
Additional comments regarding the P0068 code
It would be advised to resolve the issues the P0068 code causes as soon as possible due to the fact that the fuel economy of your vehicle may suffer due to this code. If any vacuum leaks exist, the air/fuel mixture will be incorrect and cause the engine to run lean during idle. Although this causes the engine to use less fuel, it also causes a loss of power which therefore decreases fuel mileage.
Need help with a P0068 code?
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This article originally appeared on YourMechanic.com as P0068 OBD-II Trouble Code: Air Assisted Injector Control Circuit High and was authored by Andrew Quinn.