Powertrain, generic · Fuel and air metering

P0100 Mass or Volume Air Flow Sensor A Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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. P0100 means the control module gets no usable signal at all. Ford uses it for a broken sensing element on digital sensors (period longer than 1.3 ms, i.e. below about 0.78 kHz, for half a second); on GM's 3.0 V6 in the Saab 9-4X it is set at 0 Hz. Many systems with voltage sensors skip P0100 and report low or high directly. The engine then runs on air mass calculated from manifold pressure, throttle angle and speed; Ford also disables start-stop.

Likely causes

Connector unplugged or corroded, signal or supply wire open
Sensor faulty internally (broken element, failed electronics)
Supply fuse or relay failed
Control module input faulty

Symptoms

  • Check engine light on
  • Rough idle, hesitation, lack of power (substitute value)
  • Hard starting or stalling
  • Higher fuel consumption

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–300
Time0.3–1.5 h

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

What to check first

  1. Inspect the connector
  2. Check sensor supply voltage and ground
  3. Look for intake leaks between sensor and throttle

Parts involved

mass air flow sensormass air flow sensor wiringsensor supply voltage

Related codes

P0101P0102P0103P0104P010AP0113

References: law.cornell.edu, fordservicecontent.com, newtonnet.co.uk, saabwisonline.com.