Changan‘s COS PRO lineup—including the COS1°, COS1° GT, and the commercial-oriented Kaicene variants—has carved out a solid niche in the mid-size SUV and light commercial segments. But like any modern vehicle, these models rely on a network of sensors to keep the wheels turning safely. And when a TPMS sensor fails, owners often discover the factory replacement carries a premium price tag and a dealership wait.
That’s where the aftermarket has stepped up. The BL-ST-042 from BH-Sens, a Baolong Technology brand, offers COS PRO owners a direct-fit alternative that doesn’t compromise on communication protocol or measurement accuracy. But before we get into the specifics of this particular sensor, it’s worth understanding what’s actually happening inside that valve stem every time you drive.
The Physics Behind Tire Pressure Monitoring
Tire pressure monitoring isn’t just about a pressure switch tripping at a threshold. Modern direct TPMS sensors like the BL-ST-042 are miniature electronic modules that measure two physical quantities simultaneously: pressure and temperature. The measurement principle relies on a MEMS (Micro-Electro-Mechanical Systems) pressure sensor—a microscopic diaphragm that deflects under applied pressure. That deflection changes the capacitance or resistance of the sensing element, which the onboard application-specific integrated circuit (ASIC) converts into a digital signal.
Temperature compensation is critical here. Tire pressure varies roughly 1 PSI for every 10°F change in ambient temperature. Without accurate temperature data, the pressure reading would be misleading, especially in climates where seasonal swings are dramatic. The BL-ST-042 measures both parameters and transmits them as a data packet over a 433MHz carrier frequency.
Signal Types and Modulation
The sensor doesn’t transmit continuously—that would drain the battery in weeks. Instead, it enters a sleep mode and wakes on a schedule or when triggered by a centrifugal acceleration switch (the sensor detects the wheel is rotating). When awake, it transmits a digital signal using FSK (Frequency Shift Keying) modulation, encoding pressure, temperature, sensor ID, and battery status into a frame that the vehicle’s receiver module can decode.
The 433MHz frequency band is the standard for most Asian and European vehicle platforms. It’s a trade-off: lower frequencies penetrate rubber and metal better but require larger antennas. Changan’s receiver modules are tuned specifically for 433MHz, which is why frequency matching is the first thing to verify when replacing a sensor.
Inside the BL-ST-042: Construction and Compatibility
The BL-ST-042 is a clamp-in design, meaning the sensor body mounts inside the wheel and the valve stem passes through the rim hole, secured by a nut. This is the most common configuration for modern vehicles—and it’s more reliable than snap-in designs for high-speed driving where centrifugal forces can distort rubber grommets.
Cosmetically, it’s an unassuming black plastic module, weighing around one ounce. But the engineering is in the details. The sensor is pre-programmed with the correct communication protocol for Changan, Kaicene, and Oshan applications—24 specific vehicle fitments in total. That’s a significant advantage over universal sensors that require programming tools and manual ID coding before installation.
The OE reference numbers—3601010BK01, 3601010MK01, and 3601010MK51—cover the range of COS PRO trims and the commercial Kaicene models that share the platform. If you’re a shop owner, that cross-reference alone saves the headache of pulling a sensor, reading its part number, and hoping the dealer has one in stock.
Measurement Range and Accuracy
The sensor operates within a typical automotive pressure range of 0 to 8 bar (roughly 0 to 116 PSI), which comfortably covers the 30–40 PSI range most COS PRO owners will run. Accuracy is typically within ±1 PSI, which exceeds the Federal Motor Vehicle Safety Standard (FMVSS 138) requirement of a 25% warning threshold.
Temperature readings range from -40°C to 125°C, accommodating both extreme cold starts in northern climates and brake-induced heat soak in mountainous driving.
What This Means for Your Shop or Fleet
Pro Tip: When replacing TPMS sensors on COS PRO vehicles, always check the production date code on the old sensor. Changan’s battery life expectancy is around 5-7 years, and if the vehicle is past that window, replace all four sensors simultaneously. Mixing new and old sensors means you’ll be doing another tire service in 12 months—and the customer will remember.
The real-world failure mode for TPMS sensors isn’t usually the pressure measurement itself. It’s battery depletion. The BL-ST-042’s battery is rated for approximately 6-7 years of normal driving, which aligns with the tire replacement cycle most owners follow. If you’re mounting new tires, it’s the logical moment to replace sensors proactively.
The pre-programmed nature of this sensor eliminates the need for a TPMS programming tool on initial installation. However, you’ll still need a relearn procedure on the vehicle side—typically a magnetic trigger or a diagnostic scan tool to teach the receiver the new sensor IDs. That’s a standard process for any shop with a decent OBD-II scanner.
Buyers Takeaway
For 2026, expect continued consolidation in the aftermarket TPMS space, with Chinese manufacturers like Baolong refining their product lines to match OEM frequency and protocol specifications more closely. The BL-ST-042 represents that trend: a factory-grade sensor at roughly half the dealer price, with fitment coverage that spans multiple Changan platforms.
| OE# 3601010BK01, 3601010MK01, 3601010MK51](https://longweiparts.com/product/bh-sens-433mhz-tpms-tire-pressure-sensor-fits-changan-kaicene-oshan-oe-3601010bk01-3601010mk01-3601010mk51-bl-st-042/”>BL-ST-042 | BH-Sens 433MHz TPMS Tire Pressure Sensor) is the part to stock if you service COS PRO, COS1°, or Kaicene vehicles. It’s also a solid option for fleets running the Oshan commercial variants. Cross-reference your customer’s VIN against the 24 applicable fitments, and you’ll be confident the sensor will communicate correctly on the first attempt.
Recommended Part: BL-ST-042 – OE-quality aftermarket part, ready to ship.
