P1114
ToyotaEngine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage/IAT - B Circuit Low Input
Medium SeverityThis diagnostic code indicates an intermittent low voltage signal from the Engine Coolant Temperature (ECT) Sensor circuit, or a low input from the Intake Air Temperature (IAT) Sensor B circuit. This fault can cause the engine control unit to receive incorrect temperature data, leading to improper fuel mixture, reduced engine performance, and decreased fuel efficiency.
⚠️ Before You Begin (Safety First)
Always ensure the engine is completely cool before attempting any work on the cooling system to prevent severe burns. Disconnect the negative battery terminal before performing any electrical inspections or repairs to avoid electrical shock or damage to vehicle components. Wear appropriate safety glasses.
Common Symptoms
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or stalling
- Difficulty starting the engine, especially when cold
- Black smoke from the exhaust
- Engine running rich (excess fuel)
- Engine may overheat or run cold (incorrect gauge reading)
Common Causes
- Faulty Engine Coolant Temperature (ECT) sensor
- Faulty Intake Air Temperature (IAT) sensor (if the 'B' circuit refers to IAT)
- Corroded, loose, or damaged electrical connector at the sensor
- Damaged or shorted wiring in the ECT or IAT sensor circuit
- Low engine coolant level (though less common for a low voltage code)
- Faulty thermostat causing actual temperature discrepancies
- Issues with the Powertrain Control Module (PCM), though rare
Frequently reported on: Toyota Camry (2000-2006), Toyota Corolla (2000-2008), Toyota Tacoma (2000-2004), Toyota 4Runner (2000-2009), Toyota Tundra (2000-2006)
Diagnostic Steps
- Locate the Engine Coolant Temperature (ECT) sensor, typically found near the thermostat housing or on the cylinder head.
- Inspect the ECT sensor's electrical connector and wiring for any signs of corrosion, fraying, or damage. Clean any corrosion with electrical contact cleaner.
- With the ignition off, disconnect the ECT sensor's electrical connector. Use a multimeter to check the sensor's resistance across its terminals while the engine is cold, and then again when it's warm (if safe to do so) to compare readings against factory specifications.
- With the ignition on, test for proper voltage reference (usually 5 volts) at the harness side of the ECT sensor connector from the PCM. Also, check for a good ground connection.
- If the ECT sensor is determined to be faulty or the wiring shows damage, replace the sensor or repair the wiring. Ensure the new sensor is properly sealed.
- Clear the P1114 diagnostic code using an OBD-II scanner and test drive the vehicle to confirm the repair. If the code reappears and the IAT sensor is suspected, repeat inspection and testing for the IAT sensor.
👨🔧 When to Call a Professional
If engine performance issues persist after replacing the sensor and thoroughly inspecting the wiring, or if you suspect a deeper electrical system issue or PCM malfunction, it is highly recommended to consult a professional automotive technician for advanced diagnostics.
Commonly Asked Questions
What does 'intermittent low voltage' mean for this code?
It means the electrical signal from the sensor to the engine's computer is occasionally dropping below the expected range, rather than consistently staying low. This can make diagnosis tricky as the fault may not always be present.
Can I drive my Toyota with a P1114 code?
While you might be able to drive, it is not advisable for extended periods. Incorrect temperature readings can cause the engine to run too rich or lean, potentially leading to poor fuel economy, increased emissions, and long-term damage to components like the catalytic converter.
Is the problem usually the ECT sensor or the IAT sensor for P1114 on a Toyota?
For P1114 specifically, the primary focus is often the Engine Coolant Temperature (ECT) sensor circuit due to its direct impact on fuel calculations. However, given the definition, it's wise to quickly inspect the Intake Air Temperature (IAT) sensor and its wiring as well.
How can I accurately test the ECT sensor at home?
You can test the sensor's resistance using a multimeter. Measure the resistance across the sensor's terminals when the engine is cold and then again after it has warmed up. Compare these readings to the resistance-temperature chart found in your vehicle's service manual or a reliable online resource specific to your car's make and model.
Will clearing the code fix the issue?
Clearing the code with an OBD-II scanner will turn off the Check Engine Light temporarily, but it does not fix the underlying problem. The code will reappear if the faulty sensor, wiring, or connection is not repaired or replaced.