Cylinder 4 Injector Circuit Low
The P0270 code means the vehicle's onboard diagnostic system has detected: Cylinder 4 Injector Circuit Low. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $100 - $400 (parts and labor)
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Common Symptoms
- Engine misfire on cylinder 4
- Rough idle
- Check Engine Light illuminated
- Reduced power and hesitation
- Fuel smell from exhaust
Probable Causes (Ranked by Likelihood)
- Short to ground in cylinder 4 injector wiring Very High
- Faulty cylinder 4 fuel injector (shorted coil) High
- Corroded injector connector pins High
- Damaged wiring harness near cylinder 4 Moderate
- PCM injector driver circuit failure Low
Step-by-Step Diagnostic Procedure
-
Measure cylinder 4 injector resistance -- should be 11-18 ohms; below spec indicates a shorted coil
-
Check for short to ground between injector signal wire and engine ground with injector disconnected
-
Swap cylinder 4 injector with another cylinder and clear codes to isolate the fault
-
Inspect injector wiring harness for heat damage or chafing against engine components
-
Test PCM driver signal at cylinder 4 connector with a noid light
Frequently Asked Questions
Can I drive with code P0270?
You can drive short distances. The engine will run on fewer cylinders, causing vibration and reduced power. Avoid extended driving to prevent catalytic converter damage.
Is cylinder 4 always the last cylinder?
On inline 4-cylinder engines, yes -- cylinder 4 is typically the rearmost cylinder. On V6 and V8 engines, cylinder numbering varies significantly by manufacturer.
Can I use a fuel injector cleaner additive instead of replacing the injector?
Fuel additives can help with clogged injectors but cannot fix an electrical short in the injector coil. P0270 is an electrical fault, so the injector or wiring must be repaired.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0270 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
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