Intake pressure sensor (MAP): P0106, P0107, P0108
The unit uses it to judge how much air enters the engine. It lies quietly: the car drives, but fuel use rises and power fades.
The intake pressure sensor (MAP) measures the vacuum behind the throttle. From that number the unit works out how much air reached the cylinders and decides how much fuel to inject. A fault here hits everything at once: mixture, ignition, idle.
A one-minute check
Open intake pressure. With the engine off and the ignition on it must equal atmospheric — about 100 kPa at sea level. If it reads zero or something meaningless, the sensor or its circuit is already faulty and there is nothing more to look at.
Start the engine: the value must drop noticeably, usually to 25-40 kPa. The engine creates vacuum and it shows at once. A value that stays atmospheric on a running engine means the sensor feels nothing — while the unit believes a great deal of air came in.
What the codes mean
P0106 — there is a reading, but it does not fit the rest of the picture. The unit compares MAP with the throttle and the revs: if the plate is closed while the pressure looks like full throttle, one of the two is lying.
P0107 and P0108 — signal on the floor or the ceiling: open circuit, short, or a disconnected plug.
The common cause people forget
The sensor is joined to the intake by a thin hose, and a crack in that hose gives exactly the same picture as a dead sensor — except the fix costs pennies. It is also a ready-made air leak: watch the fuel trims, they will move to plus.
Why it costs more than it looks
A lying MAP does not break the car at once — it keeps the mixture wrong all the time. Fuel use rises, soot builds up, the catalyst suffers. So a code that «does not stop you driving» is still worth closing: you pay for it anyway, in fuel and in parts.
