What P0104 means
P means powertrain (engine and transmission). The 0 marks a generic code defined by SAE, so the same number means the same thing across makes. The third character, 1, places it in the fuel and air metering subsystem; the last two digits identify the specific fault.
The MAF sensor sits in the intake duct between the air filter and the throttle and reports how much air the engine is drawing in. The engine computer uses that figure as the primary input for how much fuel to inject, so a MAF error shows up quickly in fuel trims and drivability.
What “Intermittent” means here
"Intermittent" (or "Erratic") means the mass air flow (MAF) sensor signal dropped out or jumped in a way a working sensor could not, but not continuously. Intermittent faults are almost always connections: a loose or corroded terminal, a chafed harness, or a wire that breaks contact with vibration or heat. Watching live data while gently flexing the harness is the classic way to catch one.
What you may notice
Symptoms depend on the vehicle and on how the module responds to the fault. Any of these can accompany P0104:
- Hesitation or flat spots on acceleration
- Rough or unstable idle
- Stalling shortly after starting
- Noticeably higher fuel use
- Lean or rich fuel trim codes stored alongside
Where to start diagnosing P0104
- Check the air filter and the intake duct for splits or loose clamps between the MAF and the throttle body; unmetered air is a frequent reason the reading disagrees with load.
- Inspect the MAF connector for corrosion and pushed-back pins.
- Compare live MAF readings at idle and at a steady 2,500 rpm with the specification for the engine.
- If the sensing element is visibly contaminated, cleaning it with a dedicated MAF cleaner is a reasonable first step before replacement.
Clear the code only after recording freeze frame data: it shows the engine speed, load and temperature at the moment the fault set, which is often the best clue to reproducing it.
Live data to watch
These standard OBD2 values relate to P0104. Support varies by vehicle; a value your car does not report will simply be missing.
| Value | What to look for |
|---|---|
| MAF air flow rate (PID 0x10) | Should rise smoothly with rpm and throttle; flat or spiky readings point at the sensor or wiring. |
| Short and long term fuel trim (PIDs 0x06–0x09) | Large positive trims at idle that fall with load suggest unmetered air. |
| Engine load (PID 0x04) | A sanity check against the MAF figure. |
Related codes
Codes from the same mass air flow (MAF) sensor family. If several are stored together, the shared part — wiring, a common reference voltage, or the component itself — is the place to start.
Further reading
Frequently Asked Questions
What does P0104 mean?
P0104 is the generic SAE J2012 code for "Mass or Volume Air Flow "A" Circuit Intermittent/Erratic". In plain terms, it means the engine computer has detected a "intermittent" fault on the mass air flow (MAF) sensor.
Can I keep driving with P0104?
Most engines fall back to a calculated air flow value, so the car usually still drives, but performance and fuel use can suffer. Avoid heavy loads until it is diagnosed.
What should I check first for P0104?
Check the air filter and the intake duct for splits or loose clamps between the MAF and the throttle body; unmetered air is a frequent reason the reading disagrees with load.
Definition source: SAE J2012 / ISO 15031-6 generic DTC definitions. This is the generic meaning that applies across makes; a manufacturer can define a code more narrowly or add its own sub-codes, so confirm against the service information for your vehicle before replacing parts. Written by the OBDAssistant engineering team — see our editorial policy.