P0068 - MAP/MAF - THROTTLE POSITION CORRELATION

There are differences between the sensors that control the computer in terms of the volume of air that enters the intake manifold. To indicate the volume of air flow the Power Train Control Module (PCM), with the objective of calculating the fuel and the form of synchronization, is based on the information of three sensors: MAP (Multiple Absolute Pressure Sensor) MAF (Air mass flow sensor) and TPS (Accelerator position sensor).

The PCM needs these three sensors to be precise, in terms of the time to open the injectors and the spark that is needed to reach the stoichiometric ratio, namely 14.5 / 1.

In the event of faults, either mechanical or electrical, by one of these sensors, causing instability in the system, the DTC code P0068 OBD2 is established.

• Malfunction light comes on.
• Low fuel efficiency.
• Engine performance is affected.
• Instability in acceleration.

The reasons why the diagnostic code P0068 OBDII can be established are:

• Fuel lines and hoses in poor condition, resulting in vacuum leaks.
• Input or connectors of the throttle body defective.
• Some piping in the air inlet may be disconnected or have cracks.
• Air filter clogged.
• Manifold Absolute Pressure (MAP) may have problems.
• The Mass Air Flow (MAF) may be defective.
• Throttle Position Sensor (TPS) in poor condition

The steps for the proper diagnosis and solution of the problems of the P0068 OBD2 fault code are the following:

• Having the engine turned off performs an inspection of the air filter. Check for loose connections or leaks in the pipes from the MAF sensor to the throttle body.
• Check the vacuum lines in the intake manifold for obstructions or cracks.
• Disconnect each one of the sensors related to this code, make sure there is no corrosion in the connectors, repair or change if necessary.
• Perform a MAF sensor test. Unplug the sensor connector and with the switch in the on position and the engine off check for 12 volts in the signal cable. If this voltage is not present, there may be cable problems. Make the necessary repair or change any defective component.
• Also check the ground of the mass air flow sensor with the connector installed. The result of this reading must be less than 100 mv. In case 12 volts are present, but not within the range in the ground circuit, the MAF sensor changes.
• Check the operation of the TPS sensor, make sure it is properly adjusted. Use a voltmeter and connect the red wire from the voltmeter to the signal wire and the black wire from the voltmeter to ground. Then with the key in the ignition position and the engine off, with the throttle closed, you must have less than 1 volt. If the accelerator advances, so will the voltage until it reaches 4 volts. If there are problems during this period, check the good condition of the cables. Change the throttle position sensor if necessary.
• Check the MAP sensor voltage. With the key in the on position and the engine off, there should be a voltage between 4.5 to 5 volts. With the engine on, the voltage should be between 0.5 to 1.5. This voltage should change according to the opening of the accelerator, if not, change it.