What causes a vacuum leak?

Vacuum leaks are commonly caused by cracked or disconnected vacuum hoses, damaged intake manifold gaskets, or a leaking throttle body gasket. They cause the engine to run lean.

How much does it cost to fix intake system issues?

Intake repairs range from $20 for a new air filter to $500+ for MAF sensor or intake manifold gasket replacement. Vacuum hose repairs are typically inexpensive.

P0109

Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent

Moderateintake

Overview

The P0109 code indicates the PCM has detected a manifold absolute pressure/barometric pressure circuit intermittent condition in the air intake system. This code relates to the components that meter and deliver air to the engine, which is essential for proper air-fuel mixture and combustion. Issues in the intake system directly impact engine performance and fuel economy.

Symptoms

Rough or unstable idle
Poor acceleration
Poor fuel economy
Reduced engine power

Common Causes

Faulty MAP (Manifold Absolute Pressure) sensor
Damaged or cracked intake manifold gasket
Faulty throttle body or throttle position sensor
Clogged air filter

Diagnosis Steps

1Connect an OBD-II scanner and read all stored trouble codes and freeze frame data
2Inspect the air filter and replace if dirty
3Clean or replace the MAF sensor using MAF-safe cleaner
4Check for vacuum leaks using a smoke machine or by spraying carb cleaner around intake connections
5Inspect the intake manifold gasket for leaks

Estimated Repair Cost

$100 — $500

Cost varies by vehicle, location, and repair shop. Includes parts and labor.

Commonly Affected Vehicles

Mazda 6Chevrolet MalibuFord FusionVolkswagen Jetta

Related Codes

P0106 P0105 P0113

More Intake Codes

P0068MAP/MAF - Throttle Position Correlation

Moderate

P0069Manifold Absolute Pressure - Barometric Pressure Correlation

Moderate

P0100Mass or Volume Air Flow Circuit Malfunction

Moderate

P0101Mass or Volume Air Flow Circuit Range/Performance

Moderate

P0102Mass or Volume Air Flow Circuit Low Input

Moderate

P0103Mass or Volume Air Flow Circuit High Input

Moderate

Frequently Asked Questions

Yes, a dirty MAF sensor can often be restored by cleaning with MAF-specific sensor cleaner. This is a common and affordable fix that should be tried before replacing the sensor.