B173d Peugeot May 2026

You do not need a mechanic for the diagnostic phase. A basic digital multimeter ($20) and an OBD2 scanner are enough.

Step 1: Clear the code and retest. Erase the B173D code, start the engine on a cold morning, and re-scan. If it returns immediately, the fault is permanent.

Step 2: Visual inspection. Open the hood. Locate the glow plug for Cylinder 4. Look for: b173d peugeot

Step 3: The Resistance Test (Disconnect the harness). Unplug the electrical connector from the glow plug control unit and test each glow plug directly at the unit's connector pins. You need the pinout diagram for your specific Peugeot engine (DV6 or DW10). For cylinder 4, you should see approximately 0.6 to 1.2 Ohms.

Step 4: The Harness Test. If the glow plug tests fine (0.6 Ohms), you need to test the wire from the control unit to the plug. Disconnect both ends and use your multimeter on continuity mode. A beep means the wire is good. No beep means the wire is broken. You do not need a mechanic for the diagnostic phase

Step 5: Swap test. If possible, swap the Cylinder 4 glow plug with Cylinder 1. Clear the codes and restart.

Fault code B173D is a body control / airbag system diagnostic trouble code (DTC) specific to Peugeot (and other PSA group vehicles like Citroën, DS, and sometimes Opel). It indicates a malfunction within the Occupant Classification System (OCS) — specifically, the system is unable to reliably confirm the "seat occupied" status of the front passenger seat. Step 3: The Resistance Test (Disconnect the harness)

The OCS determines:

An ounce of prevention is worth a pound of cure.