|Trouble Code||Fault Location||Probable Cause|
|P0106||Manifold absolute pressure (MAF) sensor barometric pressure (BARO) sensor -range/performance problem||Intake/exhaust leak, wiring, MAP sensor, BARO sensor|
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What Does Code P0106 Mean?
OBD II code P0106 is defined as “Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem”, and is set when the PCM (Power Train Control Module) detects a signal voltage from the MAP (Manifold Absolute Pressure) sensor that is abnormal with regard to the current engine load or throttle position, or a signal voltage that does not show a valid relationship with the MAP sensor.
Changes in the signal voltage is interpreted by the PCM as variations, or fluctuations in the intake manifold pressure when compared with ambient atmospheric pressure. In most applications, the PCM will detect and store code P0106 when an incorrect signal voltage is present for more than four continuous seconds, with reference to a signal voltage that applies to each particular application.
In terms of operating principles, the PCM uses data from the MAP sensor related to the pressure, or vacuum in the intake manifold to monitor the engine load in order to calculate an appropriate fuel delivery strategy for the current engine load, as well as the proper air/fuel ratio for that load. Note however that some applications use a BARO (Barometric) sensor that is incorporated into the MAF (Mass Airflow Sensor) instead of a dedicated MAP sensor. In these cases, the BARO sensor senses changes in ambient air pressure as a vehicle’s altitude above sea level changes.
Still other applications make use of a combined MAF/BARO sensor with a redundant, but integrated MAP sensor as a backup should the MAF sensor fail. In yet another variation, the ECM (Engine Control Module) in some cars use data from the MAP sensor to monitor the EGR (Exhaust Gas Recirculation) system, in addition to checking the validity of data from other sensors.
From this is should be obvious that other codes could accompany P0106; if other codes are indeed present, these codes should be investigated first, since P0106 could be set as the result of malfunctions and failures in systems that are not directly related to the MAP sensor.
While there are some design differences between MAP sensors made by different manufacturers, all MAP sensors are located on the inlet manifold. The image below shows the typical location of MAP sensors on four cylinder engines.
Note: A Range/Performance related code will be set when either a sensor or other component does not perform within the range the PCM (Powertrain Control Module) expects to see, given the current engine load/speed, and information gathered from other sensors. The possible causes of Range/Performance codes are likely to be defective sensors as easily as they are likely to be the result of wiring issues that affect the operation of the affected sensor or component, which means that with these codes, it is important to regard all sensors and components as part of the control circuit the code refers to.
What are the common causes of code P0106 ?
Typical causes of code P0106 are many and varied. In some cases, the code could be set as the result of unrelated faults, such as:
- Serious, or prolonged misfires on one or more cylinders
- Clogged catalytic converter(s)
- Vacuum leaks as the result of poor maintenance
- Defective throttle position sensor
- Defective, or malfunctioning mass airflow sensor.
- Defective Exhaust Gas Recirculation valve
- Defective Idle Air Control Motor
- Other causes that are directly related to the MAP sensor include:
- Open, shorted, or damaged wiring
- Defective BARO sensor (where fitted)
- Defective MAP sensor
- Unmetered air entering the inlet tract.
- Power Train Control module failure is possible, although it is relatively rare.
What are the symptoms of code P0106 ?
Common symptoms of code P0106 are for the most part the same on all applications, although the severity of some symptoms may vary from vehicle to vehicle. Common symptoms include, but may not be limited to-
- Hesitation upon acceleration
- Increased fuel consumption
- Illuminated Check Engine light
- Stored trouble codes, of which P0106 may be only one.
How do you troubleshoot code P0106 ?
NOTE: it is important to clean the MAF sensor “hot wire” element with an approved cleaning agent as a first step in the diagnostic procedure. In many cases, a simple cleaning of the MAF sensor will resolve the issue, as will a thorough check of all electrical connectors and wiring in the circuit to correct bad connections due to corrosion or damage to connectors / wiring. Also, check the exhaust system for leaks, and repair any leaks found before starting an electrical diagnosis. Be sure to test the system after each step in the diagnostic/repair procedure to ensure a reliable repair.
If there is no visible damage to wiring and connectors, make sure that the engine is in proper working order, with no misfires, lean conditions, etc. present before attempting to diagnose this code.
NOTE: Vacuum system leaks are far more common than sensor failures, so make sure that no unmetered air enters the intake tract that could cause code P0106 to be set. Repair vacuum leaks as required. Also bear in mind that a restricted airflow can also cause code P0106 to be set, so check for ruptured or restricted air inlet ducting, clogged catalytic converter(s), or clogged/dirty air filter elements. Repair/replace components as required.
If the air inlet ducting checks out OK, check the MAP sensor, or MAF/BARO sensor circuit for power, ground, and continuity, but be sure to disconnect all control modules before performing continuity checks. Check the reference voltage and ground at the sensor connector, and compare the reading to the value specified for the application being worked on.
With the ignition “ON”, and the engine “OFF”, there should be a steady reference voltage of around 5 Volts, and a good ground. The third wire in the connector is the MAP sensor signal wire leading to the PCM. Use an appropriate wiring diagram for the application to determine the correct color-coding for the wires in the connector. Repair wiring as required to restore continuity, and/or power supply.
If all readings obtained fall within the manufacturer specifications, test the sensor itself by using the manufacturer’s pressure to Hertz chart or table. Replace the sensor if it does not comply with the manufacturer’s specifications.
To test the repair, test drive the vehicle with a data-streaming tool connected, and keep a close watch on the RPM, throttle position, engine load, and road speed. Compare these values to the displayed PID (Parameter ID); the voltage from the MAP sensor should fluctuate with changing engine speed and load, with typical values varying from around 5V or slightly less on acceleration, to around 1V or a little more during deceleration.
TIP: To further ensure a successful repair, perform a vacuum test of the MAP sensor while the data steaming tool is still connected, with the ignition “ON”, but the engine “OFF”. Connect a vacuum pump to the sensor, and draw a vacuum of about 18 to 20 inches. The voltage output should drop from around 5V to about 1V as the vacuum is being drawn. Hold the vacuum for few minutes; there should be no discernable drop in both the voltage and vacuum.
With the sensor under vacuum, jiggle the connector about to see if the voltage fluctuates, but also check all vacuum hoses, caps, and the sensor seal if it plugs directly into the inlet duct. A vacuum test is the most reliable way to trace vacuum leaks that occur through hardened, split, and badly fitting hoses and connections. Repair all vacuum leaks as required.
In most cases, the above steps should resolve the issue, but to be sure, clear all fault codes, retest the vehicle, and rescan the system to see if any codes have returned. If any faults do return, there may be an intermittent fault, which can sometimes be very challenging to trace and resolve. In some cases, it may be necessary to allow the fault to worsen before an accurate diagnosis can be made.
NOTE: If despite repeated repair attempts the code(s) and symptoms persist, it is possible that the Power Train Control Module has failed, or is in the process of failing. However, this happens only rarely, but when it does happen, the PCM will require reprogramming.
Replacing the PCM should be the last resort; if all other repair attempts fail to resolve the issue, check to see if the EGR valve and Idle Air Control Motor are fully functional, since failures or malfunctions in these components can also cause code P0106 to be set on some applications. Moreover, a failed or malfunctioning Idle Air Control Motor causes a very low idle, which is easy to mistake for a failure of MAP/MAF/BARO sensors and circuits.
Codes Related to P0106
P0105 – Relates to Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
P0107 – Relates to Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
P0108 – Relates to Manifold Absolute Pressure/Barometric Pressure Circuit High Input
P0109 – Relates to Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent
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