The QG251K5 3-Pin Air Pressure Sensor is a dedicated core component for the air brake system of buses, coaches and commercial vehicles. It is installed on the vehicle air storage cylinder and air circuit pipeline to monitor the real-time air pressure of the pneumatic braking system. The sensor converts pressure changes into standard electrical signals and transmits accurate data to the vehicle dashboard and ECU system. It displays real-time air pressure values and triggers low-pressure alarm reminders. This part ensures stable air brake system operation, avoids braking failure caused by insufficient air pressure, and guarantees driving and braking safety for commercial vehicles.
| Specification |
Details |
| Product Name |
Bus Special 3-Pin Air Pressure Sensor |
| Model Number |
QG251K5 |
| Brand / Manufacturer |
Zhejiang Automobile Instrument Co., Ltd. |
| Pin Type |
3-Pin Connector |
| Thread Specification |
M12×1.5 |
| Measuring Range |
0 ~ 1.0 Mpa |
| Alarm Pressure |
0.45 ~ 0.5 Mpa |
| Application |
Bus, Coach, Commercial Vehicle Air Brake System |
| Function |
Real-time air pressure detection, transmit pressure signal to dashboard air gauge |
| Shell Material |
Zinc Alloy Plated Housing |
| Connector Material |
High-strength Insulating Plastic |
| Working Medium |
Compressed Air |
| Feature |
High precision sensing, good pressure resistance, reliable sealing, stable signal output |
| Supply Ability |
5000 Pieces / Month |
| Packing Method |
Individual Neutral Paper Box with Shockproof Foam, Outer Export Carton |
| MOQ |
Negotiable |
| Aftermarket Usage |
Replacement & Maintenance for Original Parts |
This QG251K5 air pressure sensor adopts standard 3-pin plug design, which matches the original vehicle wiring harness perfectly without modification. It is equipped with M12×1.5 standard mounting thread, featuring high fitting accuracy and firm installation. The sensor shell is made of high-quality galvanized zinc alloy, with strong compression resistance, deformation resistance and wear resistance. The internal high-precision sensing chip supports a pressure measuring range of 0–1.0MPa, with accurate induction and stable data output. It supports normal operation in complex vehicle environments, with excellent waterproof, dustproof and anti-corrosion performance. The product is produced according to original factory standards, specially customized for bus and coach air brake systems, with strong model compatibility.
1. High sensing accuracy, sensitive pressure response, no data delay or drift, effectively preventing false alarms and missing alarms of vehicle air pressure.
2. Durable alloy shell structure, strong shock and vibration resistance, adaptable to long-term bumpy driving of commercial vehicles, long service life.
3. Standard 3-pin interface and universal thread size, plug-and-play, convenient for direct replacement and after-sales maintenance.
4. Excellent overall sealing performance, effectively preventing air leakage, dust and water ingress, stable performance in high and low temperature environments.
5. Original factory quality standard, widely compatible with mainstream bus and coach models, stable quality and high cost performance.
6. Strictly tested for pressure resistance and aging resistance, suitable for long-term continuous operation of vehicle air brake systems.

1. Turn off the vehicle engine and release all residual air pressure in the vehicle air storage cylinder to ensure zero air pressure in the pipeline before installation.
2. Remove the old faulty air pressure sensor with a professional tool, and clean the mounting thread and mounting base to remove dust, rust and dirt.
3. Check the new QG251K5 sensor thread and sealing ring to confirm no damage or deformation.
4. Screw the sensor into the mounting hole manually first, then tighten it with a tool to ensure vertical and firm installation, avoiding excessive force to prevent thread slipping.
5. Align the 3-pin connector with the original harness interface and insert it firmly to ensure tight and stable connection.
6. Start the vehicle, inflate the air brake system, observe the dashboard air pressure display and low-pressure alarm function to confirm normal operation without air leakage and fault codes.
1. Do not knock, drop or squeeze the sensor body during transportation and installation, which will damage the internal precision sensing elements.
2. Must release pipeline air pressure before disassembly and installation; operation with pressure will cause safety hazards and sensor damage.
3. Do not use excessive force when tightening the thread to avoid thread slipping, shell cracking and air leakage.
4. Ensure the 3-pin connector is fully inserted; loose connection will cause abnormal pressure signal and instrument display failure.
5. Keep the sensor and connector away from water, oil and corrosive liquids to avoid short circuit and sensor failure.
6. Do not modify or cut the plug and wiring structure at will, which will affect the original electrical matching performance.
7. Regularly check the sensor tightness and sealing condition during daily maintenance to prevent air leakage failure.
8. It is forbidden to use non-matching sensors, which will cause inaccurate air pressure display and affect braking system safety.