However, before you just replace the bulb, it's worth checking a couple of things:
* Check the bulb itself: It's the most obvious, but sometimes bulbs can seem fine even when blown. Remove the bulb and inspect it carefully. Look for a broken filament inside.
* Check the bulb holder: Make sure the bulb is properly seated in the holder. Sometimes poor contact can prevent the bulb from working.
* Check the fuse: Although less likely, a blown fuse in the indicator circuit could also cause this. Consult your Citroen ZX's owner's manual to locate the fuse box and identify the correct fuse for the indicators. A multimeter can help confirm if the fuse is blown.
* Wiring: While less common, there might be a break or short in the wiring to the passenger-side front indicator. This is harder to diagnose and might require a more in-depth check of the wiring harness.
If replacing the bulb and checking the fuse doesn't solve the problem, it's probably best to seek the help of a mechanic to diagnose the more complex wiring issues.
