Code Definition

P1203 — Injector Circuit Open / Shorted - Cylinder #3

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Generic

About P1203

P1203 is a manufacturer-specific powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1203 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit; and a short-circuit (voltage pulled to ground or to supply) in the monitored circuit.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1203 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This code relates to the fuel injector control circuit for cylinder number 3 specifically. The engine control module fires the number 3 injector by switching its control circuit, pulsing the ground side while battery voltage feeds the other side of the injector. DTC P1203 is set when the module detects that the cylinder 3 injector circuit is electrically open or shorted, meaning the circuit resistance or current is outside the expected range when the injector is commanded. When this code is set cylinder 3 may misfire or drop out entirely, causing a rough idle, lack of power, hard starting, and...

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