OBD-II Error Code P0115 - Engine Coolant Temperature Circuit

OBD-II Standard OBD-II Major Fuel and Air Metering

Model: SAE J2012 Standard | Code: P0115

Applicable Systems
OBD-II

Symptoms

The check engine light illuminates. The engine may run rich, have poor fuel economy, fail to enter closed-loop operation, or experience hard starting. The ECT sensor circuit has a malfunction.

Possible Causes

  • Faulty engine coolant temperature (ECT) sensor
  • ECT sensor wiring open or shorted
  • Corroded ECT sensor connector
  • Damaged wiring harness to ECT sensor
  • Low engine coolant level causing air pocket at sensor

Troubleshooting Steps

  1. Step 1: Connect an OBD-II scan tool and read all stored DTCs and freeze frame data
    All DTCs and freeze frame data are retrieved
  2. Step 2: Inspect the related sensor or actuator wiring for damage, corrosion, or loose connections
    Wiring and connectors are in good condition
  3. Step 3: Use a digital multimeter to check sensor voltage, resistance, and reference signals per manufacturer specifications
    Values are within specified range
  4. Step 4: Perform component-level testing of the suspected sensor or actuator
    Component passes or fails definitively
  5. Step 5: Clear codes and road test to verify repair
    Code does not return and system operates normally

How to Reset

To reset code P0115: 1) Repair the underlying fault. 2) Use an OBD-II scan tool to clear the DTC. 3) Perform a drive cycle to verify the monitor completes. 4) If the code returns, further diagnosis is needed. Caution: Do not clear codes without fixing the root cause.

Frequently Asked Questions

  • Q: What does OBD-II code P0115 mean?

    Code P0115 indicates: Engine Coolant Temperature Circuit. This is a SAE J2012 standard diagnostic trouble code related to Fuel and Air Metering.

  • Q: Is code P0115 serious?

    Severity: Major. Immediate attention is recommended to prevent further damage.

  • Q: Can I drive with code P0115?

    It is not recommended to drive with this code active as it may cause further damage or safety issues.

  • Q: How do I fix code P0115?

    Diagnose the Fuel and Air Metering system, check wiring and connectors, test the related sensor or actuator, and replace faulty components as needed.

Related OBD-II Standard Fault Codes

Source: SAE J2012 Standard - Powertrain Diagnostic Trouble Codes

Category: OBD-II