Fuel & air metering · Powertrain · generic (SAE-defined)
P0108: Manifold Absolute Pressure/Barometric Pressure Circuit High Input
P0108 means the manifold absolute pressure (MAP) sensor signal voltage is higher than the engine computer expects, which can make the engine run rich.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0108 sets
The powertrain control module (PCM) monitors the MAP sensor signal against an upper limit. If the signal stays above that limit for a set time, P0108 sets. This can result from an open ground, a signal wire shorted to voltage, a failed sensor or, in some cases, a real high-pressure condition such as a disconnected sensor hose. Exact limits vary by manufacturer.
Common causes of P0108
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Failed MAP sensor
- Open sensor ground
- Signal wire shorted to voltage
- Disconnected or cracked MAP vacuum hose
- Large vacuum leak or low engine vacuum
- Corroded connector
P0108 symptoms
- Check engine light on
- Rich running, fuel smell or black smoke
- Rough idle
- Poor fuel economy
- Hesitation
How P0108 is diagnosed
- Scan for codes and freeze frame data
- Inspect the MAP hose and sensor mounting for leaks
- Compare MAP to barometric pressure with key on, engine off
- Measure ground and signal circuits at the connector
- Check engine vacuum with a gauge if the sensor reads high at idle
- Replace the sensor if the circuit and vacuum supply are good
Typical fixes for P0108
- Replace the MAP sensor
- Repair an open ground or wiring short
- Replace a cracked or disconnected vacuum hose
- Repair vacuum leaks
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0108 FAQ
What does code P0108 mean?
P0108 means the manifold absolute pressure (MAP) sensor signal voltage is higher than the engine computer expects, which can make the engine run rich. The standard definition is "Manifold Absolute Pressure/Barometric Pressure Circuit High Input."
Can I drive with a P0108 code?
Usually yes for a short period, but rich running, poor mileage and rough idle are common. Have it repaired within a few days to protect the spark plugs and catalytic converter.
Why does P0108 cause rich running?
A high MAP signal tells the PCM the engine is under heavy load, so it adds more fuel than needed.
Can low engine vacuum set P0108?
Yes. Problems such as a large vacuum leak or incorrect valve timing can raise manifold pressure enough to set it, so check mechanical condition if the sensor tests good.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.