Cause
Open circuit in lamp wiring
A break in the wiring to a warning lamp or indicator the module drives and monitors. Modules check their own output circuits, so a lamp whose circuit is open is detected and reported even though nothing about the vehicle's function has changed.
The lamp being dead is the real consequence and it is worth taking seriously. A warning lamp that cannot illuminate cannot warn, so a genuine fault later goes unannounced — which matters most for the lamps that indicate a system has degraded rather than failed. The code is the only thing left telling you the warning system is broken.
A blown bulb is the commonest cause on vehicles that still use them, and it is indistinguishable from a broken wire at the module: both are an open circuit. Check the bulb first, then the holder, then the harness — corroded holders are frequent, and on instrument clusters the fault is often a failed driver inside the cluster rather than anything external. A lamp that works while its circuit is reported open points at the monitoring circuit rather than the lamp.
Typically a moderate job.
Codes this can cause (4)
Codes where this is a likely explanation first, rather than merely a possible one.
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