OBD-II Code · Fuel & Air
P0270
Cylinder 4 Injector Circuit Low
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.
Cyl 4 injector low voltage.
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
- Misfire cyl 4
- Check engine light
Likely causes
- Failed injectorMost common
- Wiring short
Read the full diagnostic procedureP0270 indicates the ECM has measured cylinder 4 injector circuit current below the expected threshold during commanded firing pulses, pointing to a s…
P0270 indicates the ECM has measured cylinder 4 injector circuit current below the expected threshold during commanded firing pulses, pointing to a shorted injector coil, a short to ground in the injector low-side harness, or a failed ECM injector driver.
Cheapest-first ladder
- ohm the cylinder 4 injector with the connector unplugged — 11-17 ohms is healthy for saturated-driver injectors, 1.5-4 ohms for low-impedance peak-and-hold; anything appreciably below the low spec confirms winding shorted-turns.
- Check harness routing — on inline-4 engines cylinder 4 is at the rear of the valve cover where it crosses the firewall brackets and brake-booster vacuum line, and on V-engines cylinder 4 may be either front-bank or rear-bank depending on manufacturer numbering, so verify FSM cylinder ID before tracing.
- Use a noid light or current clamp to confirm the ECM is still pulsing the driver; verify 12 V supply on the injector feed.
- Caveat: on Honda K-series and Toyota 2AR engines the cylinder 4 injector connector sits directly under valve-cover breather hose drips, so connector corrosion mimics circuit-low for several thousand miles before fully failing — inspect connector pin condition before condemning the injector.
Vehicle-specific patterns2006-2011 Honda Civic 1.8L (R18A1) — cylinder 4 injector connector corrosion from valve cover breather drip, clean pins and replace pigtail before fu…
- 2006-2011Honda Civic 1.8L (R18A1) — cylinder 4 injector connector corrosion from valve cover breather drip, clean pins and replace pigtail before full injector.
- 2007-2014Toyota Camry 2.5L (2AR-FE) — internal injector winding short, replace 23250-0H050.
- 2005-2010Subaru Impreza/Forester 2.5L (EJ253) — injector harness chafe against the boxer engine bracket near the rear bank, repair and reloom.
- 2008-2013GM Equinox/Terrain 2.4L (LAF/LEA) — cylinder 4 injector internal short under GM PIP5235, replace 12638530.
Estimated repair$80 to $480.
Look up another code
P0270 — frequently asked
What does a P0270 code mean?
Cyl 4 injector low voltage.
What causes a P0270 code?
Common causes: Failed injector; Wiring short.
What are the symptoms of a P0270 code?
Typical symptoms: Misfire cyl 4; Check engine light.
Is it safe to drive with a P0270 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 P0270 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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