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.

P0104

Mass or Volume Air Flow Circuit Intermittent

Moderateintake

Overview

The P0104 code indicates the PCM has detected a mass or volume air flow 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

Check Engine Light (MIL) illuminated
Reduced engine power
Poor acceleration
Whistling or hissing noise from intake

Common Causes

Clogged air filter
Faulty MAP (Manifold Absolute Pressure) sensor
Vacuum leak in intake manifold or hoses
Dirty or faulty Mass Air Flow (MAF) sensor

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

Subaru LegacyFord FusionVolkswagen JettaKia Optima

Related Codes

P0174 P0101 P0106

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.