OBD Guide

P1240

Injector Circuit Open Cylinder 4

P1240 is an OBD-II diagnostic trouble code meaning: Injector Circuit Open Cylinder 4. Common causes: malfunction of the injector of the 4th cylinder, open or short circuit in wiring. Estimated repair cost: $17–89.

Severity
⚠️ Medium
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$17–89 (est.)

Symptoms

  • Unstable engine operation
  • Misfire in cylinder 4
  • Reduced engine power
  • Increased fuel consumption
  • Check Engine Light Is On

Causes

  • Malfunction of the injector of the 4th cylinder
  • Open or short circuit in wiring
  • Poor contact in the injector connector
  • Malfunction of the injector power supply relay
  • Problems with the engine control unit

How to Fix

  1. Check the resistance of the injector of the 4th cylinder
  2. Inspect the wiring harness and connectors for damage.
  3. Check for voltage at the injector
  4. Test or replace the injector if necessary
  5. Check the operation of the injector relay

Related codes

Error P1240 by Vehicle Brand

FAQ

What does the P1240 code mean?

P1240 is an OBD-II diagnostic trouble code that indicates: Injector Circuit Open Cylinder 4

What causes a P1240 error code?

The most common causes of P1240 include: Malfunction of the injector of the 4th cylinder; Open or short circuit in wiring; Poor contact in the injector connector; Malfunction of the injector power supply relay.

How do I fix a P1240 diagnostic trouble code?

To fix P1240: Check the resistance of the injector of the 4th cylinder. Inspect the wiring harness and connectors for damage.. Check for voltage at the injector. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1240?

Do not drive — repair immediately

How much does it cost to fix P1240?

The estimated repair cost for P1240 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat