MQ-6 LPG gas sensor: specs and pinout
Semiconductor (SnO2) sensor with high sensitivity to LPG (propane). Its resistance falls as gas concentration rises. Numbers are from the Winsen MQ-6 manual; the maker of the supplied sensor is not stated and other makers' MQ-6 sheets differ. Learning and experiment use only, not a gas alarm.
Specs
| Spec | Value | Source |
|---|---|---|
| Target gas / detection range | LPG (propane): 300 to 10000 ppm | source MQ-6 Technical Parameters |
| Heater voltage VH | 5.0 V +/- 0.1 V, AC or DC | source Technical Parameters, Standard Circuit Conditions |
| Circuit (loop) voltage Vc | Circuit voltage Vc 24 V DC (do not exceed); test circuit uses 5.0 V +/- 0.1 V | source Technical Parameters |
| Load resistance RL | Adjustable | source Technical Parameters |
| Heater resistance RH | 26 ohm +/- 3 ohm at room temperature | source Technical Parameters |
| Heater consumption PH | 950 mW max | source Technical Parameters |
| Sensitivity S | Rs in air / Rs in 2000 ppm C3H8 is at least 5 | source Technical Parameters |
| Output voltage Vs | 2.5 V to 4.0 V in 2000 ppm C3H8 (test circuit) | source Technical Parameters |
| Preheat time | Over 48 hours before first use | source Technical Parameters |
| Standard test conditions | 20 C +/- 2 C, 55 % +/- 5 % RH | source Technical Parameters |
Power
| Value | Source | |
|---|---|---|
| Supply | Heater 5.0 V +/- 0.1 V; circuit voltage up to 24 V DC | source Technical Parameters |
| Current | Heater: up to 950 mW, about 190 mA at 5 V (derived: 0.95 W / 5 V) | source Technical Parameters |
Chip pins
These are the pins of the chip on the module, from the chip datasheet. The module's own header may label or expose them differently.
The module board (header labels, load resistor, comparator and analog or digital output) is not covered by the maker's sensor manual. Pin numbers above are for the bare 6-pin sensor.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 2 and 5 | Heater electrodes (bare 6-pin sensor) | 5.0 V +/- 0.1 V | Bare-sensor pin numbers, not module header labels. | source Cautions 1.7 and Fig 8 |
| 1 and 3 (tied), 4 and 6 (tied) | Test electrodes (bare 6-pin sensor) | Vc up to 24 V DC, with series load RL | Applying voltage to pins 1 and 3 or 4 and 6 can break the leads. | source Cautions 1.7 and Fig 8 |
Build with it
Project ideas for the MQ-6 LPG gas sensor. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Raw reading display for learning: Learning project, not a gas alarm: shows how the raw value drifts during the long preheat. The heater draws about 190 mA at 5 V (derived: 0.95 W / 5 V), within USB limits. If the module has an analog output, read it on a 5 V board.
- A sensor data recorder with an Arduino Uno, an MQ-6 module and a DS3231 clock module that prints timestamped raw readings to the serial monitor: Learning project, not a gas alarm: use the record to study baseline drift and the preheat period. No threshold action is attached.
- Humidity effect on the baseline: Learning project, not a gas alarm: the maker's Fig 4 shows temperature and humidity change the sensor's resistance ratio, so reading them together makes that visible.
Common mistakes
- Reading values right after power-up: the maker specifies a preheat of over 48 hours for first use, and a sensor kept unpowered for a long time needs 48 to 168 hours of aging (source)
- Wrong heater voltage: VH is 5.0 V +/- 0.1 V; higher voltage can damage the heater (source)
- Exposing it to silicone vapour, sealants or corrosive gas: this permanently reduces sensitivity (source)
Not covered by the official source
- Winsen's v1.3 manual (hosted on a mirror) is used for every number. Other makers' MQ-6 sheets differ: an older copy (hosted on a mirror) gives a heater of 31 ohm, 900 mW and +/- 0.2 V, and is not used for numbers.
- Operating temperature range is not stated in the v1.3 manual.
- Module board electronics are not covered; hazard sensor: only display, recording and learning ideas are given.