P0106

P0106 Manifold Absolute Pressure Rationality

Circuit Description
The powertrain control module (PCM)/engine control module (ECM) uses the Manifold Absolute Pressure (MAP) sensor to control the fuel delivery and the ignition timing. The MAP sensor measures the changes in the intake manifold pressure which results from engine load (intake manifold vacuum) and the rpm changes due to Throttle Position (TP) changes and converts these changes into voltage outputs. The PCM/ECM can detect if the MAP sensor is not responding to the TP changes by comparing the actual MAP change to a predicted MAP change based on the amount of TP change that occurs. If the PCM/ECM does not see the expected MAP change or more, a Diagnostic Trouble Code (DTC) P01 06 will set.

Conditions for Setting the DTC
- DTCs P0107, P0108, P0117, P0118, P0122, P0123, P0201, P0202, P0203, P0204, P0300, P0351, P0352, P0402, P0404, P0405, P0406, P0506, P0507, P1404, P1441, P1627 not set.
- Engine running.
- Valid Barometric (BARO) pressure update.
- A/C steady state.
- Torque Converter Clutch (TCC) steady (A/T)
- No power steering cramp.
- No TP sensor fail conditions present.
- No MAP fail conditions present.
- Change in Idle Air Control (IAC) is less than 4 counts.
- Coolant temperature is greater than 14 °F (-10 °C).
- Change in rpm is less than 200.
- Change in TP sensor is less than 6%.
- Change in Exhaust Gas Recirculation (EGR) is less than 6%.
- rpm is between 1300 and 4500.
- All the above are stabilized for 0.78 seconds.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The PCM/ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.
- The PCM/ECM will substitute a fixed MAP value and use the TP to control the fuel delivery (scan tool will not show defaulted value.)

Conditions for Clearing the MIL/DTC
- The MIL will turn off after three consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm-up cycles without a fault.
- DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
With the ignition ON and the engine stopped, the manifold pressure is equal to atmospheric pressure and the signal voltage will be high. This information is used by the PCM/ECM as an indication of vehicle altitude. Comparison of this reading with a known good vehicle with the same sensor is a good way to check the accuracy of a suspect sensor. Readings should be the same ± 0.4 volts.

The MAP sensor vacuum source should be thoroughly checked for restrictions at the intake manifold.

Step 1 - 10:

Test Description
Numbers below refer to the step numbers on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the occurred. The information is then stored on the scan tool for later reference.
2. A sensor that displays an ignition ON, engine OFF BARO value that does not appear normal for the altitude the vehicle is in should be considered to be malfunctioning.
3. While starting the engine, the MAP sensor should detect any changes in the manifold pressure. This test is to determine if the sensor is stuck at a value.
4. A normal MAP sensor will react as quickly to the throttle changes as they can be made. A sensor should not appear to be lazy or catch up with the throttle movements.
5. This step checks if the reason for no MAP change was due to a faulty sensor or vacuum source to the sensor.
6. The MAP sensor vacuum source should be thoroughly checked for restrictions. A drill bit can be used to clean out any casting flash that may exist in the vacuum port.
7. The MAP sensor vacuum source should be thoroughly checked for restrictions. A drill bit can be used to clean out any casting flash that may exist in the vacuum port.
9. The MAP Sensor System Performance diagnostic may have to complete several tests before determining if the diagnostic has passed or failed the last test. Operate the vehicle in the Conditions for Setting the DTC several times to ensure that the diagnostic runs enough tests to pass or fail.
10. If no faults have been found at this point and no additional DTCs were set, refer to "Diagnostic Aids' for additional checks and information.