P0105 OBD2 Code Guide
P0105 is a sensors diagnostic trouble code. Use this hub to understand the plain meaning, the first checks to run, and which vehicle-specific guides may be more useful before replacing parts.
Manifold Absolute Pressure (MAP) / Barometric Pressure Circuit Malfunction
The P0105 code indicates that the Powertrain Control Module (PCM) has detected an electrical malfunction within the Manifold Absolute Pressure (MAP) sensor circuit or the Barometric Pressure (BARO) sensor circuit. The MAP sensor measures the absolute pressure within the intake manifold, providing crucial data to the PCM for calculating engine load, fuel delivery, and ignition timing. A BARO sensor, often integrated into the MAP sensor or PCM, measures atmospheric pressure. A "circuit malfunction" means the PCM is receiving an implausible signal, no signal, or a signal outside its expected operating range, which can severely impact engine performance, fuel economy, and emissions.
Code verification standard
P0105 is published with SAE J2012 / ISO 15031-6 code structure plus OBD2 P0105 diagnostic context.
First checks
- - Read all stored and pending codes before clearing anything.
- - Save freeze-frame data so you know speed, load and temperature when the code set.
- - Inspect wiring, connectors, fuses, hoses and obvious leaks tied to the named system.
- - Compare live data against realistic values before buying sensors or modules.
- - Clear the code only after repair and complete a drive cycle to confirm it does not return.
P0105 diagnostic path
- 1Visual Inspection & Vacuum Check: Begin by visually inspecting the MAP sensor, its electrical connector, and the vacuum hose connected to it (if applicable) for any signs of damage, corrosion, or disconnections. Check for any obvious vacuum leaks around the intake manifold or associated hoses that could affect MAP sensor readings.
- 2MAP Sensor Voltage Test: With a multimeter, back-probe the MAP sensor connector to measure the reference voltage (typically 5V), ground, and signal voltage. Compare the signal voltage to manufacturer specifications at key-on-engine-off (KOEO) and at idle. A healthy MAP sensor should show high voltage (near reference) at KOEO (atmospheric pressure) and drop significantly at idle (manifold vacuum).
- 3Wiring Harness Integrity Check: Disconnect the MAP sensor and the PCM connectors. Use a multimeter to check for continuity and resistance in the MAP sensor's signal, reference, and ground wires between the sensor connector and the PCM connector. Look for opens, shorts to ground, or shorts to power.
- 4PCM Input Verification (Scan Tool): Use a diagnostic scan tool to monitor the live data stream for the MAP sensor reading (in kPa or inHg). Compare this reading to the BARO sensor reading (if available) at KOEO – they should be very close. Observe how the MAP reading changes with engine RPM and load. A stuck, erratic, or absent reading indicates a sensor or circuit issue.
Verify before repair
- - Replace the faulty MAP sensor.
- - Repair or replace damaged wiring and connectors in the MAP sensor circuit.
- - Locate and repair any vacuum leaks affecting the intake manifold pressure.
- - Clean or replace the throttle body if excessive carbon buildup is affecting manifold pressure readings.
Vehicle-specific pages to check next
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