Code P0107: Explanation, Symptoms, and Solutions
The trouble code P0107 is a generic OBD-II code that indicates a circuit problem with a too low input signal from the MAP sensor (Manifold Absolute Pressure). This sensor plays a crucial role in measuring the air pressure in the intake manifold. The Powertrain Control Module (PCM) uses this data to accurately calculate the air-fuel mixture ratio and regulate ignition. An abnormally low signal triggers the check engine light and stores the P0107 code.
MAP Sensor Operation and Causes of Code P0107
To understand the origin of the fault, it is essential to know the operating principle of the sensor:
- The PCM sends a 5-volt reference voltage to the MAP sensor.
- A variable resistor inside the sensor changes this voltage based on the pressure (vacuum) present in the intake manifold.
- The signal voltage returned to the PCM thus typically varies between 1 volt (low pressure, high vacuum) and 4.5 volts (atmospheric pressure).
- The P0107 code specifically triggers when the PCM detects a signal voltage constantly below 0.25 volts, indicating a circuit problem or a faulty sensor.
Symptoms of Code P0107
A failing MAP sensor or a defective circuit manifests through several symptoms that can affect driving:
- Hard starting or unusually long cranking time.
- Unstable idle, irregular, or intermittent stalling, especially at idle.
- Hesitation, power loss, and cut-outs during acceleration.
- Emission of black smoke from the exhaust (overly rich mixture).
- Noticeable increased fuel consumption.
- Illumination of the check engine light (MIL) on the dashboard.
Possible Causes of P0107 Fault
The origins of this code are mainly electrical or mechanical:
- Faulty MAP sensor (most common cause).
- Electrical circuit problems:
- Short to ground in the MAP signal wire.
- Open circuit or poor connection in the signal wire, the 5V reference, or the ground.
- Oxidized, loose, or damaged MAP sensor connector.
- Short circuit on the 5-volt reference circuit caused by another sensor (on some Chrysler models, for example).
- Significant vacuum leaks at the intake manifold or the sensor connection.
- Failing PCM (extremely rare, always check as a last resort).
Diagnosis and Solutions: How to Fix Code P0107
Follow this logical diagnostic procedure to identify and correct the fault.
Step 1: Visual Inspection and Data Reading
- Visually inspect the MAP sensor connector and wiring for obvious signs of damage, corrosion, or disconnection.
- Using an OBD2 diagnostic tool, observe the live data MAP signal voltage value (engine running at idle). A value stuck below 0.5V confirms the problem.
Step 2: Checking Power Supplies and Grounds
- Engine off, unplug the MAP sensor connector.
- Using a multimeter, measure the voltage between the 5V reference pin and the ground pin at the harness. You should measure 5 volts.
- If absent: check the circuit back to the PCM. A short circuit on the 5V line (caused by another sensor) is possible.
- If present: proceed to the next step.
- Check the continuity of the sensor ground.
Step 3: Testing the Sensor and Signal Circuit
- Plug the connector back in and turn the ignition on (without starting). Measure the voltage on the signal wire.
- If the voltage is still very low (<0.5V), unplug the sensor again. If the voltage rises to ~5V, the MAP sensor is faulty and must be replaced.
- If the voltage remains low even with the sensor unplugged, there is a short to ground in the signal wire that needs repair.
- Vacuum Test (optional but conclusive): Using a vacuum pump, apply vacuum to the MAP sensor. The signal voltage should decrease progressively. If it does not vary, the sensor is defective.
Step 4: Final Checks
- Thoroughly inspect the intake manifold and hoses for possible vacuum leaks that could skew the measurements.
- Gently shake the sensor harness and connector while the engine is idling to detect an intermittent problem.
Pro Tip: After any repair, clear the trouble codes with your diagnostic scanner and perform a road test to ensure the P0107 code does not return.
Codes Related to P0107
- P0105: MAP Sensor Circuit Problem.
- P0106: MAP Circuit Range/Performance.
- P0108: MAP Signal Too High.
FAQ: Frequently Asked Questions about Code P0107
Can I drive with a P0107 code?
It is strongly discouraged to drive for a long time. Engine performance is degraded, and increased fuel consumption can damage the catalytic converter.
Can a MAP sensor be cleaned?
No, it is a sealed electronic and pneumatic component. Cleaning is generally not effective, and replacement is the recommended solution.
Don’t feel comfortable performing this diagnosis yourself? This code often requires the use of a multimeter. If you are not equipped or familiar with auto diagnostics, consult a professional mechanic for an accurate diagnosis and guaranteed repair.