It’s a familiar Monday morning ticket: a 2020 Audi A6 Prestige rolls in with the air suspension warning lit and the tail sitting an inch lower than the customer remembers. Owner swears the compressor is dying. Half the parts counters in town will happily sell him one. Nine times out of ten, though, the compressor is fine — and the real culprit is a $40–$80 level sensor nobody bothered to check first.
Diagnose Before You Quote
Modern air suspensions rely on ride height sensors — small potentiometer units bolted to the suspension linkage, with a plastic arm riding a ball socket on the control arm or axle. Road spray, salt, and simple age kill them three ways: the electrical track wears out, the ball joint develops play, or the linkage arm snaps entirely.
Before condemning anything, get the car on a scan tool and look at actual measured vehicle height values versus specified values, key on engine off. If one corner reads wildly out of range while the others sit normal, you’ve found your sensor. Wiggle the arm gently while watching live data — a signal that jumps or drops out confirms it. I’ve watched shops quote four-figure compressor jobs when a ten-minute sensor swap would have closed the ticket.
Common mistake: Replacing the compressor because the car “pumps constantly.” A failing height sensor feeds the module bad data, and the module pumps to compensate. Check the sensor signal first, every time.
Why the OE Number Beats Any Model List
Here’s where fitment gets tricky. On the current-generation Audi sedan and SUV platforms, the same core sensor design appears across multiple models and trim levels, and equipment packages change which corners carry sensors at all. Aftermarket listings often compress all of that into a single line item, which is exactly why “it fits my car, right?” is the wrong question to ask a catalog page.
The right question is: what does the number on my old sensor say? For this application, that’s OE 4K0941286B. Pull the wheel, drop the skid plate if needed, read the stamping on the housing, and match it character for character. If the car’s still drivable, a VIN-based lookup through your supplier works too — just don’t trust a generic year/make/model filter alone. And count the sensors while you’re under there; plenty of these cars run two per axle, so budget accordingly.
Also photograph the old unit’s connector and lever orientation before you order. Ten seconds with your phone saves a return shipping label later.
The Straightforward Fix
Once the OE number is confirmed, this becomes an easy job. Something like the OS-HSA078 OS-HSA078 | OSRAM Ride Height Sensor | Fits Audi | OE# 4K0941286B — an OSRAM-built replacement matched to 4K0941286B — drops in with basic hand tools: unclip the arm, unbolt the bracket, swap the connector. Torque is light; don’t gorilla the plastic mounts.
Two shop notes worth passing along. First, after installation, most of these cars need a quick adaptation or basic-settings routine through the scan tool so the module relearns the new sensor’s center point — skipping it can leave you with a warning light and an angry callback. Second, check that the arm sits mid-travel at standard ride height before you button everything up; a misrouted clip will skew every reading downstream.
If the stamping on your old sensor reads 4K0941286B, the OS-HSA078 OS-HSA078 | OSRAM Ride Height Sensor | Fits Audi | OE# 4K0941286B is the no-drama order — correct connector, correct arm geometry, no adapter games. Verify the number first, and this repair stays a one-hour ticket instead of a week-long parts shuffle.
Recommended Part: OS-HSA078 – OE-grade replacement, in stock now.
