P0108 — Manifold Absolute Pressure/Barometric Pressure Circuit High Input

powertrain (engine/transmission)

Is it safe to drive?

Drive cautiously until repaired P0108 is usually not an immediate stop-driving condition, but incorrect manifold pressure data can cause rough running, hesitation, poor fuel control, or stalling. Avoid prolonged driving if those symptoms are severe.

Typical symptoms

The check-engine light illuminates and P0108 is stored in the powertrain controller
Engine idle becomes rough, unstable, or noticeably surges
Acceleration may hesitate or stumble, especially at low engine speed
The engine may stall, hesitate during starting, or be difficult to keep running
On turbocharged vehicles, P0108 can cause incorrect airflow calculations and insufficient boost

Common causes

A faulty MAP/barometric pressure sensor with an internally shorted or failed signal element
The MAP sensor signal wire shorted to the 5-volt reference or battery voltage
Corroded, damaged, or water-contaminated MAP sensor connector terminals
A high-resistance or improperly connected sensor ground or 5-volt reference circuit
Incorrect sensor terminal arrangement following a previous wiring or component repair
An ECM-side wiring or internal circuit failure after the sensor and harness checks pass

How to diagnose with an OBD scanner

Document P0108 with an OBD2 scanner Connect an OBD2 scanner, such as an ELM327 adapter used with AIScanAuto, and read stored, pending, and freeze-frame data. Select live MAP sensor data and compare the displayed pressure and signal voltage with the model-specific expected values.
Check the MAP sensor and connector Locate the MAP/barometric pressure sensor and inspect its connector for pushed-back pins, bent terminals, corrosion, oil contamination, or water intrusion. Repair damaged terminals or replace the connector before condemning the sensor.
Test the signal circuit Using the vehicle wiring diagram, back-probe the MAP signal terminal with a multimeter while lightly moving the harness. Confirm that P0108 is not caused by the signal being shorted to the 5-volt reference or battery voltage.
Verify reference voltage and ground Confirm that the MAP sensor receives the proper reference voltage and has a low-resistance ground. Check for voltage drop across suspect ground connections and compare all measurements with the manufacturer specifications for that sensor.
Repair and validate the fault Replace a failed MAP sensor or repair the confirmed wiring, connector, reference, or ground fault. Clear P0108, restart the engine, verify that live MAP pressure changes correctly with engine load, and confirm the code does not return.

Approximate repair cost

Typical independent-shop cost is approximately USD 100-350 for diagnosis and a common MAP sensor or wiring repair, depending on vehicle accessibility and labor time. Figures are estimates and vary by region.

Common questions

What does code P0108 specifically mean?

P0108 means the controller is receiving an excessively high signal from the manifold absolute pressure/barometric pressure circuit, commonly from the MAP sensor or its wiring.

Is P0108 the same as a low-pressure fault?

No. P0108 identifies a high electrical input, while the opposite circuit condition is normally reported as a low input under a different code.

Can the vehicle still be driven with P0108?

It may be driven cautiously if the engine runs smoothly, but stalling, severe hesitation, or unstable idle should prompt immediate diagnosis and repair.

What should be checked first for P0108?

Start with live MAP sensor data and a visual connector inspection, then test the signal, reference voltage, ground, and harness for shorts before replacing the sensor.

When your check engine light comes on and a code reader spits out P0108, the engine control unit has detected a problem with the signal from either the manifold absolute pressure (MAP) sensor or the barometric pressure sensor. P0108 specifically means the voltage on that sensor circuit is reading higher than it should—typically close to battery voltage instead of the lower signal range the computer expects. The PCM groups this fault under powertrain codes, which cover anything affecting engine or transmission operation.

The MAP sensor measures the pressure inside the intake manifold, while the barometric sensor tracks atmospheric pressure. Both readings help the computer calculate air density and determine how much fuel to inject and when to fire the ignition. When P0108 sets, the PCM sees a "circuit high" condition—meaning the voltage on the MAP/barometric circuit has climbed above the acceptable window. Physically, this points to one of three scenarios: the signal wire is shorted to a power source, the ground return for the sensor is broken, or the sensor itself is failing in a way that pulls the line high.

The engine control module monitors this circuit constantly while you drive. Once the voltage stays outside the expected range for enough consecutive drive cycles, the PCM stores P0108 and turns on the warning light. The freeze frame data saved alongside the code is diagnostic gold—it records engine speed, load, temperature, and vehicle speed at the exact moment the fault occurred, giving you the best starting point for tracking down the root cause.

Common Symptoms of P0108

Check Engine Light illuminated
Engine stalling or dying when coming to a stop
Limp-home mode activating with noticeably reduced power output
Sluggish or unresponsive throttle
Rough, unstable, or higher-than-normal idle speed

Common Causes of P0108

Failed MAP or barometric pressure sensor pulling the signal high
Signal wire shorted to battery positive somewhere in the harness
Open or broken ground return for the MAP/barometric sensor
Contaminated or malfunctioning MAF or MAP sensor
Wiring or connector damage in the intake air metering circuit
Vacuum leaks downstream of the MAF sensor
Faulty throttle position sensor or accelerator pedal position sensor

How to Diagnose P0108

Plug in an OBD2 scanner, confirm P0108 is stored, and record the freeze frame data—this shows what the engine was doing when the fault triggered.
Scan for any other diagnostic codes. Related trouble codes often point to the real culprit. Also look up manufacturer TSBs for your specific make and model—many P0xxx issues have known factory fixes or software updates available through the manufacturer website or NHTSA database.
Perform a visual inspection of the wiring harness and connectors associated with the MAP/barometric circuit. Look for chafed insulation, broken wires, corrosion, and loose or pushed-out pins.
With the MAP sensor disconnected, back-probe the signal wire at the harness connector and measure voltage. A high reading with the sensor unplugged confirms a short to power in the wiring. If the voltage drops to normal reference range, the sensor itself is the problem.
Inspect the throttle body for carbon buildup and check that the throttle plate moves freely through its full range without binding.
Monitor MAP/MAP and throttle position sensor values in the scanner's live data stream while slowly pressing the accelerator pedal—the numbers should change smoothly and proportionally.

Repair Options for P0108

Address the most affordable and probable causes before spending on major components:

Throttle body cleaning: $80–$200
MAF or MAP sensor replacement: $150–$400
Throttle body assembly replacement: $250–$700

How Much Does It Cost to Fix P0108?

The total bill hinges entirely on which part is actually at fault. Parts and labor at independent shop rates in USD typically break down as follows:

Cleaning the throttle body runs $80 to $200. Swapping in a replacement MAF or MAP sensor generally costs $150 to $400. If the entire throttle body assembly needs replacing, expect to pay between $250 and $700. Most P0108 repairs end up somewhere in the $80 to $700 range depending on the diagnosis. Getting an accurate diagnosis before purchasing parts is the smartest move—the worst-case scenario is rarely the first thing to check.

Can You Drive with P0108?

Drive with caution. Many throttle-related faults trigger limp-home mode, which limits power output enough to get to a repair shop but not safely for extended highway driving. If the engine stalls completely or the accelerator pedal becomes unresponsive, stop driving immediately and have the vehicle towed.