Park any Audi built in the last two decades close to a wall and you’ll hear it — that metronome beep turning frantic as your rear bumper closes in. The sound comes from a component most owners never think about until it dies: the ultrasonic parking sensor. OSRAM’s OS-PASA002 is a direct replacement for a batch of these units, and it happens to be a good excuse to explain what’s actually going on behind your bumper.
The Physics: Echoes and Simple Arithmetic
Every parking sensor on the road uses the same trick bats do. A ceramic piezoelectric disc inside the housing flexes when voltage hits it, vibrating at roughly 40 to 48 kilohertz — well above human hearing. It fires a short acoustic burst, then flips into listening mode. Sound travels at about 343 meters per second, so the control module takes the echo’s round-trip time, halves it, and gets the gap between bumper and obstacle.
The math really is that crude, which is why the systems are cheap and dependable. Refinements matter, though. Cold air slows sound by roughly 0.6 m/s per degree Celsius, so better sensors compensate for temperature. And there’s a hard physical limit: the transducer can’t register anything closer than about 25 centimeters, because the echo arrives before the disc stops ringing. That’s the blind zone every owner rediscovers the expensive way.
Signal Types: One Wire or a Network
Here’s where generations split. Older Audi platforms — the C5-era cars among them — run comparatively simple hardware. Each sensor reports back on its own line as an analog voltage, and a dedicated control unit translates that into beeper cadence and dash display. Newer vehicles multiplex everything onto a LIN bus, with each sensor carrying its own ID and digital payload.
This matters when you’re buying a replacement, because a sensor isn’t just a microphone in plastic. Its acoustic damping, transmit power, and signal timing have to match what the module expects. Get it wrong and you get erratic beeping, phantom alarms, or a corner sensor the car flat-out ignores.
The OS-PASA002 Up Close
| Attribute | Detail |
|---|---|
| Brand | OSRAM |
| Part type | Ultrasonic parking sensor |
| OE cross-references | 7H0919275B, 4B0919275G |
| Coverage | Five Audi applications |
The OS-PASA002 | OSRAM Parking Sensor | Fits Audi | OE# 7H0919275B, 4B0919275G carries both OE numbers, which tells you it replaces units fitted across multiple production runs rather than one narrow model year. For independent shops, that consolidation is the whole point — one SKU covering five applications means fewer mis-ordered boxes on the shelf.
Where does a quality aftermarket unit actually differ from the OE part in daily use? Two places. First, beep consistency: the cadence needs to track the dash display exactly, or drivers lose trust in the system. Second, longevity. Budget sensors usually die from moisture creeping through the potting compound, not from the transducer wearing out. OSRAM’s sealing record across their lighting and sensing lines has been solid, and this unit follows the same build approach.
Who should buy: anyone chasing an intermittent chirp or a dead corner on a covered application who wants OE-equivalent behavior without dealer pricing. Who should skip: owners of late-model, bus-based cars — always match your OE number first, since these references won’t cross to newer platforms.
And if your Audi has started crying wolf at empty air, or gone silent on one side entirely, the OS-PASA002 | OSRAM Parking Sensor | Fits Audi | OE# 7H0919275B, 4B0919275G deserves a look before you pay dealer rates for the same hardware in a fancier box.
Recommended Part: OS-PASA002 – In stock – a direct-fit OE-grade replacement.
