P0203 indicates the powertrain control module (PCM) has detected an electrical fault in the fuel injector circuit for cylinder 3. This usually means the circuit is open, shorted to ground or voltage, or has resistance outside the expected range.
The injector's internal coil may be open or shorted, or its connector may be damaged, causing the PCM to see an out-of-range circuit.
Chafed, pinched, or broken wires, along with corroded or loose terminals between the injector and PCM, can create opens or shorts.
Terminal tension loss, corrosion, or moisture intrusion can cause high resistance or intermittent contact in the cylinder 3 injector circuit.
Incorrectly routed, spliced, or pinned wiring from earlier work can introduce intermittent opens or shorts on this specific injector circuit.
The PCM's internal transistor or driver for cylinder 3 can fail, but this is uncommon and should only be considered after the injector and wiring are ruled out.
It is usually safe for short trips, but a misfiring cylinder can overheat the catalytic converter and cause further damage, so it should be repaired promptly.
Usually no. PCM injector driver failure is uncommon; replace or reprogram the PCM only after the injector, connector, and wiring have been thoroughly tested and the driver is confirmed faulty.
No. P0203 is an electrical circuit fault. A mechanically clogged injector more commonly causes a misfire code rather than an injector circuit code.
Yes. P0203 refers specifically to the electrical circuit for the cylinder 3 fuel injector.