Technical Description of OBD-II Trouble Code
Low Input in Manifold Absolute Pressure/Barometric Pressure Circuit
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to vehicles equipped with OBD-II. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
The Manifold Absolute Pressure (MAP) sensor detects changes in the vacuum pressure of the intake manifold. The sensor receives 5 Volts of power from the PCM (powertrain control module).
Inside the MAP sensor, there is a resistor that moves in response to the manifold pressure. The resistor adjusts the voltage between approximately 1 volt to 4.5 volts (depending on the engine load), and this voltage signal is sent back to the PCM to indicate the manifold pressure (vacuum). This signal is crucial for the PCM to determine the amount of fuel to deliver. A P0107 DTC is triggered when the PCM detects that the MAP signal voltage is below 0.25 volts, which is considered too low.
An example of a MAP sensor
Potential Symptoms
When the MAP sensor signal is low, the vehicle will likely experience difficulty starting. Other symptoms may include:
Causes
The causes of a low MAP sensor signal circuit (P0107) could be any of the following:
Possible Solutions
First, using a scan tool with the Key on and engine running, monitor the MAP sensor voltage. If it reads less than 0.5 volts, turn off the engine, unplug the MAP sensor, and use a DVOM (Digital Volt/Ohm Meter) to check for 5 Volts on the 5 Volt reference circuit.
1. If there is no 5 Volts on the reference circuit, check for the reference voltage at the PCM connector. If the reference voltage is present at the PCM connector but not at the MAP connector, repair the open in the reference circuit between the PCM and MAP harness connector. If 5 Volt reference is NOT present at the PCM connector, check the powers and grounds of the PCM and repair or replace them as necessary. (NOTE: On Chrysler products, a shorted Crank sensor, Vehicle speed sensor, or any other sensor that uses the 5 Volt reference from the PCM can cause a short in the 5 Volt reference. To fix this, simply unplug each sensor one at a time until the 5 Volt reference reappears. The last sensor unplugged is the shorted sensor.)
2. If you have a 5 Volt reference at the MAP connector, connect the 5 volt reference circuit to the signal circuit. Then, check the MAP voltage on the scan tool. It should be between 4.5 and 5 Volts. If it is, replace the MAP sensor. If not, repair any open or short in the signal circuit wiring and re-check.
3. If everything appears to be in order, perform a wiggle test. Start the engine and manipulate the harness, connector, and tap on the MAP sensor. Take note of any changes in voltage or engine speed. Repair the connector, harness, or sensor as necessary.
4. If the wiggle test yields no issues, use a vacuum pump (or your lungs) to create a vacuum on the MAP sensor vacuum port. As you apply vacuum, the voltage should decrease. With no vacuum, the MAP sensor should read approximately 4.5 volts. If there is no change in the MAP sensor reading on the scan tool, replace the MAP sensor.
MAP Sensor DTC’s: P0105, P0106, P0108, and P0109.
