Air pressure sensor

A MAP sensor reads the air pressure inside the intake manifold and sends that reading to the engine computer in real time. The ECU turns manifold pressure into engine load, and from load it sets the fuelling and the ignition timing, so this one small reading shapes how the whole engine runs.The name is short for manifold absolute pressure sensor, and the usual map sensor location is on or beside the intake manifold. It's a small plastic body held by a single screw, with its element in the airstream and a plug on top. Turbocharged cars often carry a second one in the boost pipe after the intercooler, and on many diesels this sensor doubles as the boost sensor.

The sensor sits in a dirty airstream, and dirt is what usually gets it. Vapours from the EGR valve and the crankcase breather bake onto the element until the readings drift. Common signs:

• Black smoke on diesels: Over-fuelling against a pressure reading that isn't true.
• Flat acceleration and weak boost: The ECU trimming fuel back to match a false low figure.
• Rough idle or stalling at junctions: Engine load miscalculated exactly when it matters most.
• Fuel economy sliding: Rich running often shows up at the pump before anywhere else.
• Check engine light with P0105 to P0109 or P0069: The circuit or its plausibility flagged by the ECU.
• A sooted or oily element on inspection: The coating that ends most of these sensors.

When a MAP sensor goes bad, the ECU works from the wrong numbers. Too much fuel brings black smoke, fouled plugs, and heavy consumption, while too little brings hesitation, flat spots, and pinking. Either way the engine light usually arrives with codes between P0105 and P0109.Parthunt24 gathers used map sensor listings from major parts marketplaces such as ProxyParts, eBay, Ovoko, TotalParts, Opisto, Ecooparts, Ricambipro, and Autoparts24 in one place. 361 offers sit together with the map sensor price, pressure range, and pin count of each shown.

Plenty of MAP sensors share the same shell, which makes them easy to mix up.Pressure range is the main trap. A naturally aspirated engine's 1-bar sensor and a turbo engine's 2.5- or 3-bar unit can share one body and one plug, so a sensor can fit and click home but still read wrongly. Only the OEM code confirms the range and calibration.Count the pins next. A three-pin unit reads pressure alone, while a four-pin T-MAP also carries the intake temperature sensor inside, and the two aren't interchangeable. Petrol, diesel, and hybrid intakes are mapped differently, some engines run a MAF sensor as well as this one, and the flange, screw hole, and O-ring have to sit flush on your manifold.Choose the car in the boxes at the left, and sensors for other engines disappear from view. Tap a result and the advert's own marketplace opens, seller, photos, and buy button together.

• Vehicle make, model, and year: MAP sensors get re-specced at facelifts even when engines carry over.
• OEM part number: The code on the body confirms range and calibration.
• Engine type and engine code: Each engine code expects its own pressure curve.
• Fuel type: Petrol, diesel, and hybrid intakes are mapped differently.
• Turbocharged or naturally aspirated engine: Boosted engines need 2.5- or 3-bar sensors rather than the 1-bar kind.
• Connector type: The plug shape and its seal must suit your loom exactly.
• Number of pins: Three-pin sensors and four-pin units with temperature differ inside.
• Pressure measurement range: The ECU converts volts to pressure on one fixed scale.
• Mounting style: One screw and an O-ring, but the flange must match the manifold.
• Condition of the sensor and connector: Oil film, soot crust, cracked bodies, or bent pins rule it out.

With the original advert open, keep in mind what usually ends these sensors.Dirt kills more MAP sensors than age does, and a sooted element isn't always the end. A careful spray of electrical contact cleaner revives many of them, which is worth knowing before you condemn your own and when you're weighing up a grubby but cheap listing.Then judge the rest:

• Photos: The element, the O-ring, the pins, and the number moulded into the body.
• Seller reputation: A long track record and buyers who received working sensors.
• Compatibility: The code checked digit by digit, since the range hides inside it.
• Included components: O-ring and screw present, or the sensor alone?
• Condition: An oily element, thick soot, hairline cracks, greened pins.
• Testing: A key-on reading near 1 bar quoted, which is what a healthy one shows.
• Warranty and returns: Good to have, since drift only shows under load.
• Shipping: The element is the fragile end, so it should travel capped.
• Documentation: The engine it served, and whether that engine smoked.

If the code matches and the element is clean, you can make the purchase via the seller’s listing on their marketplace of choice.

The manifold absolute pressure sensor is among the cheaper engine sensors, and the map sensor price mostly follows what's packed inside the shell.A plain used map sensor for a popular engine costs about €5-€20, a genuine four-pin T-MAP €20-€45, and turbo-specific or rare versions €45-€90.On Parthunt24 these start from 5.00. What sets one map sensor price apart from the next:

• Pins and functions: A T-MAP with temperature inside outprices the plain kind.
• Pressure range: Boost-rated sensors come from fewer donor cars.
• Brand marking: A stamped original is easier to verify than a blank shell.
• Engine rarity: Map sensors for sale from common engines are inexpensive.
• Element condition: A clean element brings better money, and it's worth paying.
• Tested reading: A listing that quotes key-on pressure has done your first check for you.

The best map sensor for your engine is simply the one that matches its code and range, so sort by price and take the cheapest that does.

Whatever coated the sensor is still in the intake, so it's worth checking the neighbouring parts on Parthunt24 while the fault is fresh:

• Intake manifold: The housing the sensor reads, with swirl flaps that stick on many diesels.
• Air intake hose: A split here lets in unmetered air and mimics a sensor fault.
• Mass air flow sensor (MAF): Measures airflow directly on engines that use both sensors.
• Intake air temperature sensor: Built into a T-MAP on many cars, separate on others.
• Air quality sensor: Reads the outside air for the cabin, and lives in the same dirty airstream.
• Throttle body: Sets the pressure the sensor sees, and carbon builds on its flap.
• EGR valve: The main source of the soot that coats this sensor's element.
• Turbocharger: Its boost is what the 3-bar versions exist to measure.

An element wet with oil means the breather system is feeding oil into the intake, so fix that first or any map sensor you fit will foul the same way.

MAP, MAF, boost, and T-MAP sensors look alike in photos, and buying by looks is how the wrong one usually arrives. An evening comparing thumbnails across a dozen tabs can still end with a near-match, a restocking fee, and a car that's no better a week later. Returns take longer than the search did. Parthunt24 works from your car instead. The results show only sensors that belong on your engine, including original bosch map sensor units, each listed with its code, range, and map sensor price.Match the number first, compare map sensor prices second, and look at the photos last.Do it that way and the right map sensor for your car is in the basket today, on the first attempt.