P0100 code meaning
Mass or Volume Air Flow Sensor A Circuit
Powertrain system Generic code P01xx codes Check engine light
What P0100 means
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.
P0100 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0100
- Check engine light on
- Rough idle, hesitation, lack of power (substitute value)
- Hard starting or stalling
- Higher fuel consumption
Common causes of P0100
- Most likelyConnector unplugged or corroded, signal or supply wire open
- Most likelySensor faulty internally (broken element, failed electronics)
- PossibleSupply fuse or relay failed
- Less likelyControl module input faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Mass air flow sensorMass air flow sensor wiringSensor supply voltage
What each part of P0100 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| 00 | The exact fault in that area. |
What to do next
- Note P0100 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0100
What does P0100 mean?
P0100 means "Mass or Volume Air Flow Sensor A Circuit". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P0100?
Drive gently and only to a workshop. With P0100 the car can go into limp mode (reduced power) to protect itself.
Will P0100 fail an emissions test?
Yes, it can. P0100 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0100 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0100 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.