P0105
Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
If your vehicle's onboard computer has flagged the diagnostic trouble code P0105, it refers to a detected anomaly regarding "Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction". This systemic engine fault needs a targeted check before symptoms expand.
Driver's Summary
When your OBD2 scanner shows P0105, the engine control module has flagged an issue specifically related to manifold absolute pressure/barometric pressure circuit malfunction. You may notice rough idle, hesitation, poor fuel economy, check engine light, all of which are direct consequences of this malfunction. This is a moderate-severity fault — plan a repair shop visit within the week to keep it from escalating.
Symptoms
Rough idle, hesitation, poor fuel economy, check engine light
Common Causes
- Faulty MAP sensor
- Broken vacuum line to the sensor
- Wiring harness damage
- Corroded electrical connector
How to Fix
- 1 Test and replace MAP sensor
- 2 Replace damaged vacuum lines
- 3 Repair wiring harness
- 4 Clean connector contacts
Technical Explanation
To set P0105, the PCM samples the affected circuit multiple times per second, comparing live readings against manufacturer-programmed operating windows. Sensor output is cross-validated against complementary sensor data (such as MAF vs. MAP correlation, or upstream vs. downstream O2 comparison) to confirm the fault is genuine and not a result of a sensor reading an actual engine condition. Once confirmed, the code is stored as a permanent DTC and the MIL is activated. The freeze frame snapshot — recording RPM, load, coolant temperature, and fuel trim at fault detection — is also saved and is critical for accurate diagnosis.
Is It Safe to Drive?
While the vehicle is typically drivable with P0105 active, avoid towing, aggressive acceleration, or extended highway driving until the fault is resolved. The primary risk is accelerated wear on faulty map sensor and broken vacuum line to the sensor.
Mechanic's Pro Tip
For P0105, always perform a smoke test before replacing any parts — unmetered air from a cracked intake boot, split hose, or failed gasket is the root cause in the majority of lean fault cases and costs almost nothing to fix. After any repair, clear the code and watch short-term fuel trim (STFT) live on a scan tool; it should recover to within ±5% at idle within 2–3 minutes if the vacuum leak is truly resolved.
MAP sensor: 50 - 150; Vacuum lines: 20