P0105: Manifold Absolute Pressure/Barometric Pressure Circuit

P0105 means the engine control unit has found a fault in the circuit of the MAP (Manifold Absolute Pressure) sensor or the barometric pressure sensor that it does not classify as simply too low (P0107), too high (P0108) or implausible (P0106). Depending on the make it covers an open or shorted circuit, or a signal that cuts in and out, which is why it is sometimes logged as intermittent. The engine then runs on a substitute pressure value, and turbocharged engines usually limit power. The cause is usually a connector, a chafed wire or the sensor itself, and most repairs land between 40 and 220 euros.

P0105 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0105 and illuminates the check engine light.

If your vehicle has triggered P0105, you may notice one or more of these symptoms:

• Check engine light on, sometimes together with a reduced power or glow plug warning
• Limp mode with capped power, common on turbocharged petrol and diesel engines, which may return to normal after the engine is switched off and restarted
• Hesitation, surging or a rough idle while the engine fuels from a substitute pressure value
• Black or dark grey smoke under acceleration on diesels, where boost and EGR control are upset
• Hard or long cranking, and noticeably higher fuel consumption
• Symptoms that come and go over bumps or when the engine rocks, pointing at an intermittent wiring fault

Here are the most common causes of P0105:

No - address this immediately. Turbocharged petrol and diesel engines can drop into limp mode on this code, and because the fault is often intermittent the power may come back after a restart and then disappear again, for example during an overtake or a motorway merge. A naturally aspirated petrol car will usually still get to a workshop, but it is fuelling from a substitute value and can hesitate, idle roughly or stall. Drive it gently and straight to a garage rather than living with it.

Follow these steps to pinpoint the root cause of P0105:

1. Read every stored code and the freeze frame. A generic OBD2 reader can do this and can show the standard live values for manifold pressure and, where the car supports it, barometric pressure. It cannot show the manufacturer's own fault detail (for example whether the fault is flagged intermittent) or run the manufacturer's tests; that needs manufacturer-level software. If other sensors on the same 5 V reference also have codes, start with the shared reference and ground
2. Switch the ignition on without starting the engine and read the MAP value. With the engine stopped the manifold is at outside air pressure, so MAP should match barometric pressure, roughly 95 to 105 kPa at sea level and lower at altitude. As a worked example, Toyota's KD diesel Hilux manual reads about 0 kPa as a short in the signal wire, and 250 kPa or more as an open or short in the 5 V feed or an open in the signal or ground wire
3. Start the engine and watch the MAP value while you wiggle the connector and flex the harness along its route. A value that drops out, spikes or freezes while you move the loom is the intermittent fault this code usually describes, and marks the spot to repair
4. Inspect the connector and harness. Look for green or white corrosion on the pins, water in the plug, a lock tab that no longer holds, and rubbing marks where the loom crosses a bracket, pulley or pipe, especially if other work was done in that area recently
5. Backprobe the plugged-in connector. The reference pin should read roughly 4.5 to 5.5 V and the sensor ground should be within about 0.1 V of battery negative. With the connector and the ECU unplugged, each of the three wires should show close to 0 ohms end to end and no continuity to body ground
6. If the wiring is sound, check that the sensor responds. A naturally aspirated petrol engine should pull roughly 25 to 45 kPa at idle and swing back toward barometric pressure when you blip the throttle. A diesel idles close to atmospheric pressure and should rise smoothly above it as boost builds under load. A sensor whose value never moves, or jumps around with the wiring left alone, is faulty
7. If P0105 returns with good wiring and a sensor that responds, the next checks need manufacturer-level software: some engines carry the barometric pressure sensor inside the ECU, and some makes list turbocharger or EGR checks for this code. Replace the ECU only after those checks, and remember that many replacement ECUs need coding or initialisation

Repair costs for P0105 vary depending on the root cause and your vehicle. Here are typical estimates:

P0105 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

These codes are often seen alongside P0105 or indicate related issues: