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Home / Codes / P0203
DTC code page

P0203: Injector Circuit/Open - Cylinder 3

Quick answer: The ECU detected an electrical fault in the cylinder 3 injector circuit.

Drivers also search this fault as cylinder 3 injector circuit, injector 3 open circuit, P0203 injector fault.

Severity: high Family: powertrain Related paths: 9
Meaning

What P0203 usually means

P0203 points to the cylinder 3 injector command path. That matters because the diagnostic order should stay focused on injector electrical integrity, not drift immediately into generic misfire parts swapping.

Fast triage

Start here before chasing parts

  • Scan first: save freeze-frame and pending codes before clearing anything.
  • Confirm the complaint: compare the stored code with current drivability symptoms.
  • Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
  • Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.
Initial checks

What to check first

  • Confirm whether P0303 or a matching balance issue appears with the injector code.
  • Inspect cylinder 3 harness routing for rub-through against brackets or covers.
  • Do not ignore recent wash, coolant, or oil contamination near the injector connector.
Driving risk

Can you keep driving?

P0203 can quickly turn into a damaging misfire if the cylinder is not fueling correctly, so minimize driving when symptoms are active.

High urgency: If symptoms are active, reduce driving and diagnose quickly before secondary damage builds.
Likely causes

Common causes behind this code

  • Bad injector coil on cylinder 3
  • Loose or corroded injector 3 connector
  • Wire damage or intermittent open on the cylinder 3 circuit
  • Shared feed or ground quality problem
  • PCM driver issue after the circuit is proven externally sound

Cause phrases often tied to this code: injector 3, connector issue, injector coil, wiring damage, driver circuit.

Diagnostic order

Suggested workflow

  1. Read freeze-frame and confirm how the engine behaved when the code set.
  2. Inspect injector 3 connector, terminals, and local harness routing.
  3. Verify injector voltage supply and command-circuit integrity.
  4. Test injector resistance and compare only against the proper specification.
  5. After repair, verify cylinder 3 contribution and misfire counts stay normal.
Avoid guesswork

Common mistakes

  • Guessing at the injector without checking the connector first.
  • Letting a visible P0303 distract from the more specific injector-circuit evidence.
  • Ignoring contamination in the connector body.
Repair path

Practical fix guidance

  • Repair the actual injector 3 circuit fault and correct the reason it failed.
  • Use secure harness routing and connector retention so the fault does not return with vibration.
  • Confirm the cylinder now fuels correctly under idle and light load.
Vehicle context

Affected brands in this MVP

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.

Aliases and common searches

English phrases tied to P0203

Useful when the driver knows the wording but not the exact DTC yet.

  • cylinder 3 injector circuit
  • injector 3 open circuit
  • P0203 injector fault
Related search intent

Queries this page can answer naturally

  • P0203 code meaning
  • what does P0203 mean
  • cylinder 3 injector problem
FAQ

Quick questions about P0203

Is P0203 more serious than P0303?

It is more specific. P0203 points directly at the injector circuit, while P0303 only says cylinder 3 is misfiring.

Can bad pin tension trigger P0203?

Yes. Loose terminals are a common reason injector circuits fail intermittently.

Should I suspect the PCM first?

No. Injector, connector, feed, and harness faults are more common and should be proven first.