Fuel & air metering · Powertrain · generic (SAE-defined)
P0100: Mass or Volume Air Flow Circuit
P0100 means the engine computer detected a general electrical problem in the mass air flow (MAF) sensor circuit, which measures how much air enters the engine.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0100 sets
The powertrain control module (PCM) reads the mass air flow (MAF) sensor signal, which may be a voltage or a frequency, and checks that it is present and plausible. If the signal is missing, erratic or outside the circuit's normal operating range in a way that does not fit a more specific high or low code, P0100 sets. Some newer definitions call this the "A" circuit.
Common causes of P0100
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Unplugged, loose or corroded MAF sensor connector
- Damaged MAF wiring, including power, ground or signal
- Failed MAF sensor
- Blown fuse or relay feeding the sensor
- Aftermarket intake disturbing the sensor
- PCM fault (rare)
P0100 symptoms
- Check engine light on
- Hesitation or stumble on acceleration
- Rough idle or stalling
- Black smoke or rich smell in some cases
- Reduced fuel economy
How P0100 is diagnosed
- Scan for codes and freeze frame; note other MAF or sensor supply codes
- Inspect the MAF connector and harness
- Check for power and ground at the MAF connector
- Watch MAF readings in live data at idle and during a rev
- Back-probe the signal wire with a meter or scope
- Replace the sensor only after confirming the circuit is good
Typical fixes for P0100
- Reconnect or repair the MAF connector
- Repair damaged wiring
- Replace a failed MAF sensor
- Replace a blown fuse and correct its cause
- Return the intake to the factory configuration
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0100 FAQ
What does code P0100 mean?
P0100 means the engine computer detected a general electrical problem in the mass air flow (MAF) sensor circuit, which measures how much air enters the engine. The standard definition is "Mass or Volume Air Flow Circuit."
Can I drive with a P0100 code?
Usually yes, since the engine computer substitutes an estimated airflow value, but performance and fuel economy may suffer. Have it repaired soon to avoid stalling and rich or lean running.
Will cleaning the MAF sensor fix P0100?
Cleaning helps with contamination-related readings but rarely fixes a circuit fault. Check wiring and connector first.
Can I drive with the MAF sensor unplugged?
Many engines will run on a backup airflow estimate, but drivability and emissions suffer and the check engine light stays on.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.