For European car specialists and DIY Audi owners alike, there’s a moment of quiet dread that comes after the air suspension warning light illuminates on the dash. The car sits unevenly in the driveway. The compressor cycles erratically. And somewhere in the parts catalog, there’s a number you need to match — but finding the right OE reference can feel like decoding a secret language.
Here’s the reality: Audi’s ride height sensor system isn’t just about ride comfort. It feeds critical data to the ABS module, the headlight leveling system, and the adaptive suspension controller. A failing sensor on a C6 A6 or D3 A8 doesn’t just make the car sag — it can trigger a cascade of warning lights and, in worst cases, put the vehicle into a reduced-power safety mode. That’s why getting the correct OE number is the difference between a clean fix and a weekend of chasing electrical ghosts.
The Anatomy of an Audi OE Number
Audi’s original equipment numbers follow a structured format that tells a story. Take the OE reference 4F0941285B. Breaking it down:
- 4F0 — This is the platform code. 4F0 indicates the C6 A6 / D3 A8 generation (2004-2011). This is your first compatibility filter.
- 941 — This designates the component family. 9-4-1 falls under the electrical/sensor category, specifically suspension-related electronics.
- 285 — The specific component identifier within that family. For ride height sensors, this typically denotes position or function within the vehicle (front left, rear right, etc.).
- B — The revision suffix. This is the part that trips up most buyers. A suffix change — from 4F0941285A to 4F0941285B — usually means Audi revised the internal electronics or the lever arm geometry. Later supersedes often include improved moisture sealing, which directly addresses the most common failure mode for these sensors.
The critical distinction: while the ‘A’ revision may physically bolt onto the same mounting point, the ‘B’ revision contains updated Hall-effect internals that output a cleaner signal curve. A used ‘A’ sensor might work for a week before the same intermittent voltage drop reappears. That’s why cross-referencing the exact suffix matters.
Cross-Brand Equivalents and the Parts Matrix
Here’s where the aftermarket gets interesting. The 4F0941285B is not an Audi-exclusive part. Volkswagen used variants of this sensor across the Phaeton (3D0 941 285) and Touareg platforms. The physical mounting pattern is identical, but the electrical output curve can differ slightly due to different suspension geometries. Swapping a Touareg sensor into an A6 without checking resistance values across the sweep range can result in an erroneous “implausible signal” fault code.
For the aftermarket, manufacturers like OSRAM — a name better known for lighting but increasingly active in vehicle sensors — have stepped in with direct-fit replacements. The OSRAM OS-HSA012 ride height sensor is engineered to match the OE 4F0941285B specification, not just the bolt pattern. This distinction matters: a generic sensor that “fits” the bracket is not the same as a sensor that matches the output voltage curve, the lever arm length, and the connector pinout. Get the lever arm length wrong by even 2mm, and your headlight leveling system will aim too high or too low.
| Specification | OE 4F0941285B | Typical Aftermarket (Generic) | OSRAM OS-HSA012 |
|---|---|---|---|
| Output Type | Analog 0.5-4.5V | Analog (often unverified) | Analog 0.5-4.5V |
| Lever Arm Length | 115mm (specific) | Varies (check spec) | 115mm (matched) |
| Connector | 3-pin (specific terminal) | 3-pin (often universal) | 3-pin (matched) |
| Operating Temp | -40°C to +125°C | -20°C to +85°C | -40°C to +125°C |
| Revision Match | Yes (B suffix) | Unknown | Yes (B suffix equivalent) |
Why the Revision Letter Is Your Best Diagnostic Tool
Let’s talk about what actually fails on these sensors. The Hall-effect unit itself is rarely the problem. The failure almost always occurs at the connector terminals or within the internal circuit board where moisture ingress corrodes the solder joints. When Audi originally developed the 4F0941285A, the connector housing lacked a proper sealing gasket. By the time the ‘B’ revision shipped, Audi had added a rubber boot around the connector interface and applied a conformal coating to the circuit board.
If you’re diagnosing a suspension level fault on a 2007 A6 and the stored code is C1712 (level control system — no signal from ride height sensor, front left), don’t just clear the code and replace the sensor. Inspect the old sensor’s connector for green corrosion. If you see it, the wiring harness side likely needs a pin-out clean and dielectric grease treatment. Otherwise, you’ll be doing this job twice.
Pro Tip: Before ordering, measure the resistance between the sensor’s signal pin and ground. On a known-good sensor, you’ll see a smooth, linear sweep from roughly 500 ohms to 2.5k ohms as you rotate the lever arm through its full range. Any dead spots or abrupt jumps indicate internal failure — and they’ll show up before the voltage output becomes erratic enough to trigger a fault code.
The Buyer’s Shortlist for 2026
For the shop owner stocking parts for the 2005-2011 A6/A8 market, the OS-HSA012 represents a solid middle ground. It’s not the cheapest option — you can find no-name sensors for under $30 if you’re willing to gamble — but it carries the OSRAM brand guarantee and, more importantly, matches the full operational temperature range of the factory part. That temperature spec matters if your customers drive in climates that see both -30°C winter mornings and 40°C summer afternoons. The cheap sensors often lose calibration accuracy at temperature extremes, producing intermittent leveling faults only when the car is cold-soaked.
One more consideration: the ride height sensor on the C6 A6 is a critical input for the headlight range control module. If you replace the sensor and skip the basic headlight aiming procedure, you’re leaving the system out of spec. The OS-HSA012 allows you to complete the VAG-COM adaptation within the factory-allowed tolerance band without needing to shim the mounting bracket — something that isn’t always true with budget alternatives.
Bottom Line
The next time you’re staring at a suspension fault on an Audi C6 or D3 platform, resist the temptation to plug in any sensor that physically matches. Decode the full OE number, check the revision suffix, and match the electrical characteristics — not just the mounting holes. The | OE# 4F0941285B](https://longweiparts.com/product/os-hsa012-osram-ride-height-sensor-fits-audi-oe-4f0941285b/”>OS-HSA012 from OSRAM) covers the 4F0941285B specification correctly, and at roughly 40-60% below dealer pricing, it puts a reliable fix within reach without sacrificing the signal accuracy Audi’s suspension controller expects.
It’s a simple part, but it performs a critical job. Pay attention to the numbers, and the car will thank you with a level stance and a quiet dash.
Recommended Part: OS-HSA012 – OE-grade replacement, in stock now.
