P010C - Mass or Volume Air Flow Sensor 'B' Circuit Low
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Mass or Volume Air Flow Sensor 'B' Circuit Low (P010C). The signal is below the lower threshold, typically from a short to ground or an internally shorted sensor.
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Mass or Volume Air Flow Sensor 'B' Circuit Low – Airflow at Idle | Signal (g/s) | 2 - 6 g/s (warm idle) | Idling, all loads off |
| Mass or Volume Air Flow Sensor 'B' Circuit Low – Airflow at 3000 RPM | Signal (g/s) | 15 - 35 g/s (no load) | Stationary, raised RPM |
| Mass or Volume Air Flow Sensor 'B' Circuit Low – Signal (Voltage or Frequency) | Voltage (V) | 1.0 - 1.7 V idle / 2.0 - 4.5 V under load (frequency type: 2 - 10 kHz) | Ignition ON / engine running |
| MAF Supply Voltage | Voltage (V) | 11.8 - 14.4 V | Engine running at connector |
Idling, all loads off
Stationary, raised RPM
Ignition ON / engine running
Engine running at connector
Oscilloscope Waveform Analysis
200 ms/div, 1 V/divPossible Causes
Short to ground on the signal wire or an internal short circuit within Mass or Volume Air Flow Sensor 'B' Circuit Low
Channel B:Verify dedicated wiring pins and signal pair for circuit B against the schematic.
Chafed or pinched wiring harness along the signal path to Mass or Volume Air Flow Sensor 'B' Circuit Low
Poor ground connection or excessive voltage drop (> 0.1 V) at the ground point for Mass or Volume Air Flow Sensor 'B' Circuit Low
Defective internal output driver or reference circuit in the control module for Mass or Volume Air Flow Sensor 'B' Circuit Low
Symptoms
4
Recommended Solution
Compare signal voltage and resistance between circuit B and companion circuit A at module connector.
Measure signal wire resistance to chassis ground with connector unplugged (must exceed 10 kΩ; low reading confirms short to ground).
Verify loaded supply voltage and harness terminal pins at Mass or Volume Air Flow Sensor 'B' Circuit Low.
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Mass or Volume Air Flow Sensor 'B' Circuit Low.
Log MAF airflow (g/s) during a wide-open-throttle (WOT) pull against target displacement specs.
Mechanic's Tip
A failing MAF often drives extreme long-term fuel trims (LTFT) without setting a direct MAF code. Always verify if trim deviation tracks airflow changes before blaming the O2 sensor.