Powertrain, generic · Fuel and air metering

P0104 Mass or Volume Air Flow Sensor A Circuit Intermittent

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The mass air flow sensor (MAF) sits between the air filter and the throttle or compressor and measures how much air the engine draws in; fuel quantity, load and ignition are calculated from it. Most are hot-film or hot-wire sensors that output either a voltage or, on GM, Saab and newer Ford systems, a frequency. P0104 covers brief dropouts or jumps in the signal without a permanent low or high fault – the classic sign of a loose contact. In Ford's 2020–2023 petrol summary the code is set once more than 25 short open or short-circuit events have been counted. GM and Saab do not list P0104 in the documents checked; there such dropouts end up under P0102/P0103 or P0101. The trip count is not stated by Ford. Diagnosis means moving the harness while watching the live signal and checking terminals for corrosion and weak tension.

Likely causes

Loose contact at the sensor connector (corrosion, spread terminals, broken latch)
Chafed or partly broken wire moved by the engine
Sensor electronics dropping out (temperature-dependent)
Poor ground or electrical interference

Symptoms

  • Check engine light on, may go out again
  • Occasional hesitation, misfire-like stumble, flat spot
  • Intermittent rough idle or stalling

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–300
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

mass air flow sensormass air flow sensor wiringsensor supply voltage

Related codes

P0100P0101P0102P0103P010E

References: law.cornell.edu, fordservicecontent.com, saabwisonline.com.