OBD-II Code · Fuel & Air
P0203
Injector Circuit Malfunction — Cylinder 3
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$100–$500
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Cylinder 3 injector circuit fault.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Cyl 3 misfire
- Check engine light
Likely causes
- Failed injector 3Most common
- Wiring
Read the full diagnostic procedureP0203 isolates the fault to the cylinder 3 injector circuit, with the same electrical logic as P0201 and P0202: the PCM saw an open, short, or driver…
P0203 isolates the fault to the cylinder 3 injector circuit, with the same electrical logic as P0201 and P0202: the PCM saw an open, short, or driver-circuit anomaly on injector 3's pulse and flagged that cylinder specifically. On inline-6 and V-configuration engines, cylinder 3 sits in the middle of one bank, which makes it a common heat-soak victim on engines where the intake routing puts the boost intercooler return or exhaust crossover near that injector's pigtail.
Cheapest-first ladder
- noid light test at the cylinder 3 connector to confirm PCM commands a pulse; resistance check at the injector (port: 11-17 ohms, GDI: 1-3 ohms) and compare to the other five or seven cylinders, looking for any injector that reads more than 0.5 ohm off the median; scope the ground-side waveform for a clean pull-down to within 0.5V of ground; finally, swap with another injector on the same bank and see if the code follows.
- The expensive misdiagnosis is replacing all six injectors on a BMW N54 at $1,800 to $2,400 when the actual failure is a single $280 injector that needs to be index-coded via ISTA.
Vehicle-specific patterns2007-2013 BMW N54 335i sets P0203 commonly because cylinder 3 is in the middle of the head and runs slightly hotter under boost, and the piezo-electr…
- 2007-2013BMW N54 335i sets P0203 commonly because cylinder 3 is in the middle of the head and runs slightly hotter under boost, and the piezo-electric injector (in early N54 cars before the solenoid retrofit under SIB 13 01 09) develops cracked piezo stacks;
- 2011-2017Ford 3.5L EcoBoost Explorer and F-150 throws P0203 from carbon-tip buildup on the middle cylinders that disrupts spray pattern;
- 2007-2013GM 5.3L LS trips P0203 from melted-connector syndrome where exhaust heat from the manifold deforms the Multec injector connector body;
- 2003-2007Honda Accord V6 J30/J35 sees P0203 from a clogged port injector that responds to a $90 BG fuel-induction service.
Estimated repair$90 to $2,400.
Look up another code
P0203 — frequently asked
What does a P0203 code mean?
Cylinder 3 injector circuit fault.
What causes a P0203 code?
Common causes: Failed injector 3; Wiring.
What are the symptoms of a P0203 code?
Typical symptoms: Cyl 3 misfire; Check engine light.
Is it safe to drive with a P0203 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $100-$500.
How do I diagnose a P0203 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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