P0105 on Volkswagen: Causes, Symptoms and Fix Cost

The Quick Answer above is the generic definition. What follows is the model-specific detail for the Volkswagen models that log P0105.

Beyond the generic causes listed on the main P0105 page, these are the patterns noted for Volkswagen models:

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

Estimated repair costs for P0105 in EUR, compiled across makes. Expect Volkswagen parts and labour towards the upper end of each range.

These codes are often seen alongside P0105 or point to related issues, on any make: