93C3

What the code means

93C3 logs a fault in the front passenger seat occupancy mat sensor. This is a matrix sensor built into the seat cushion that detects whether the seat is occupied.

The SRS (Supplemental Restraint System) uses that signal to decide how the passenger seat should behave. With a faulty sensor, the control module misreads the seat state — the airbag light comes on and/or false seatbelt warnings appear.

Typical causes: damage to the sensor mat from wear, moisture exposure, or physical damage, plus removing or replacing the seat upholstery without recoding the sensor afterward.

Symptoms

Indication:

• The airbag light is on in the instrument cluster.

Warnings:

• A passenger seatbelt warning (chime and indicator) appears even when nobody is in the seat.

When it shows up:

• In some cases the fault only sets when a passenger is sitting in the seat.
• After the sensor is disconnected or replaced without recoding, the fault stays.

Diagnosis and repair

1. Pull the fault codes with a diagnostic scanner — INPA, ISTA, or NCS Expert.
2. Check the seat for electronics or moisture that could affect the sensor.
3. Inspect the wiring under the seat for damage and corrosion.
4. If the sensor is faulty, the options are:

• Replace the sensor (OEM part number 25 52-10-1-...).
• Install a bypass emulator that cancels the signal and turns the light off.
• Recode the new sensor with NCS Expert.

1. After the repair or replacement, clear the faults and verify the system works.

Knock-on problems

• If you ignore the fault, the airbag system may not work correctly in a crash: the module won't know whether the passenger seat is occupied.
• Deployment logic can go wrong — the airbag may fail to deactivate on an empty seat, or it may deploy incorrectly with a passenger present.