When was FREY founded, and what does it do?

FREY was founded in 2004. Its stated activities include automotive aftermarket parts research and development, production, operations, sales, service, and import and export.

Which vehicle brands does FREY principally cover?

FREY identifies Mercedes-Benz, BMW and Land Rover as its principal vehicle-brand applications. Its homepage states that it offers more than 16,000 SKUs.

What warranty and after-sales response commitments does FREY publish?

FREY's quality page publishes a warranty of 2 years or 60,000 km, a 24-hour quality diagnosis commitment and a 48-hour troubleshooting commitment.

What quality-control process does FREY describe?

FREY states that it uses inspection equipment, a quality-management system and a quality-control team, with inspection of every product. Its published quality principles include review of the quality-control process, avoidance of product defects, control of the entry and exit of defects, and quality improvement.

Which certifications and catalogue-data qualifications does FREY state?

FREY's quality page states ISO 9001 certification and TÜV certification under the heading OE Quality Standard. It also states that FREY has met TecDoc and TecAlliance data-maintenance quality requirements and obtained the qualification of a high-quality parts certification data supplier.

What warehouse and export figures does FREY publish?

FREY's homepage states more than 42,000 square metres of warehouse space, exports to more than 150 countries and more than 500 employees. It also states that each product is individually packaged.

What information appears in FREY's product catalogue?

FREY's catalogue entries include FREY product numbers, reference numbers and vehicle applications. Published brake-disc entries also include dimensions, thickness, minimum thickness, hole count and weight.

How can customers contact FREY?

Overseas contacts are 0086 18028634956 and freymarketing@cnfrey.com. China contacts are 400-1080-878 and 001@cnfrey.com. The published address is Room 101, 9-1, South 1st Street, Qishan Village, Xiuquan Street, Huadu District, Guangzhou City, China.

Home/Mercedes-Benz brake wear sensor – diagnose & fit

Mercedes-Benz brake wear sensor – diagnose & fit

Diagnose before you replace

Brake Warning Light Fault & Fitting Playbook

A lit brake warning lamp does not always mean a worn pad. Trace the Mercedes-Benz brake wear sensor circuit, check the rear routing and clip seating, then verify before condemning the part. The same procedure applies to any brake pad wear sensor on the listed chassis.

Check fitment for OE 2115401717 Contact Us

OE 2115401717 FREY 780700101 Rear, with retaining clip MOQ 100

Brake wear sensor OE 2115401717, rear, with retaining clip — FREY 780700101 — Brake wear sensor OE 2115401717 — rear unit, supplied with retaining clip.

Symptom Triage: What the Driver Reports

Start from the symptom, not the part. Each row points to the module that resolves it.

Symptom	Most likely cause	Go to
Lamp on solid, pad visibly worn	The sensor loop has been severed by friction material.	Circuit logic below, then fitment.
Lamp on, pad thickness looks fine	Clip not seated or lead chafed — the loop is open without wear.	Routing and clip modules.
Intermittent lamp	Loose connector, damaged loom or lead standing off the pad.	Verification module before buying anything.
Lamp on right after a pad change	Clip fitted the wrong way round, or the connector not fully latched.	Clip placement and verification.

Why the Circuit Opens When the Pad Wears

The sensor is a closed contact loop embedded in the pad. As friction material wears down, the loop is eventually cut. An open circuit is the signal — the warning lamp is not reading pad thickness, it is reading continuity.

This is why a severed wire and a worn pad produce exactly the same lamp. The circuit cannot tell the two apart, so the diagnosis has to: check continuity at the connector, then inspect the lead before assuming the pad is worn.

Keep that model in mind for the next two sections — routing and clip seating are the two ways a good sensor produces a false "worn" signal.

Rear Sensor Location & Caliper Routing

Four landmarks to check with the wheel off. These are spatial checks, not torque steps.

Caliper body

The rear sensor sits at the caliper with the lead running toward the pad backing plate.

Connector end

Locate the connector first; the lead between it and the pad is what you are inspecting.

Damper and spring seat

Check for chafing where the lead passes the damper or spring seat at full droop.

Caliper bracket

Confirm the lead is not trapped behind the bracket — a common mis-route that reads as intermittent.

Mis-route alert: a lead that looks fine at ride height can chafe only at full droop. Turn the wheel lock-to-lock and re-check the two points above.

Retaining Clip Placement & Orientation

The sensor is supplied with a retaining clip. Orientation is the difference between a seated sensor and an intermittent fault.

Do

Seat the clip so the lead sits flat against the pad backing plate and the clip clicks into its groove. "Seated" means the lead cannot be lifted away with light finger pressure.

Don't

Fit the clip the wrong way round. The lead then stands off the pad, reads as intermittent rather than worn, and the lamp can come back days later.

Do

Re-check the clip after the caliper is back on — removing and refitting the caliper can pop it out of its groove.

Don't

Force the lead into a tight radius to make it fit. A kinked lead is a future open circuit.

Verification Before You Condemn the Part

Work through these checks in order. Replacing a sensor that is still continuous just moves the fault.

01Unplug the connector and check continuity across the sensor loop.

02Inspect the lead for chafe at the two routing points from the previous section.

03Check the loom side of the connector for corrosion or pushed-back pins.

04Confirm the clip is seated with the lead flat against the pad.

Stop / go gate: replace the sensor only if the loop reads open and the lead and connector show no damage. If continuity is present, the fault is in the loom or the cluster — investigate there before ordering a part.

Fitment Snapshot — OE 2115401717 → FREY 780700101

OE number: 2115401717
FREY number: 780700101
Position: Rear, supplied with retaining clip
Weight: 0.010
MOQ: 100
Chassis: W221 · W220 · W212 · W211 · W203 · W204 · W169 · W245 · W166

Brake wear sensor OE 2115401717 rear with retaining clip

Brake wear sensor OE 2115401717 connector end

Brake wear sensor OE 2115401717 lead and clip detail

Coverage & Fitment FAQ

How many models does this sensor cover?

The current catalogue lists 759 applications across the nine chassis codes on this page (W221, W220, W212, W211, W203, W204, W169, W245, W166). Counts move as the catalogue updates.

Is this the front or the rear sensor?

This is the rear brake wear sensor, supplied with a retaining clip. Front fitment is not claimed for this part number.

What model years are covered?

The product meta states 1995–2023 coverage. Confirm the chassis code against the fitment snapshot before ordering.

Is the retaining clip included?

Yes — the product image and description state the rear sensor is supplied with the retaining clip.

What is the minimum order quantity?

MOQ is 100 for this part number.

My chassis is not listed — can you confirm fitment?

Send the OE number on the existing part and the chassis code. Fitment is confirmed against the catalogue before an order is placed.