P0114 – Intake Air Temperature Circuit Intermittent

P0114 is an OBD-II generic code that indicates the engine coolant temperature (ECT) sensor is reporting readings outside the normal range. This code requires prompt attention as it can lead to poor engine performance, increased emissions, and potential engine damage if left unaddressed.

Urgency and Severity

• P0114 is considered a moderately severe code. In most cases, you can continue driving cautiously for a short distance, but it's best to diagnose and fix the issue as soon as possible.
• Avoid driving long distances or under heavy load until the problem is resolved. Overheating can cause serious engine damage.
• If the check engine light is flashing or you notice signs of overheating (temperature gauge in the red, steam from engine, etc.), pull over immediately and have the vehicle towed to a repair shop.

Code Details

• P0114 is a generic powertrain code that applies to all makes and models of vehicles with OBD-II[.
• The last two digits (14) refer to the specific fault – in this case, an issue with the engine coolant temperature sensor circuit.
• While the general diagnosis steps are similar across vehicles, always consult the factory repair information for your particular make and model for detailed specifications and procedures.

Parts Involved

The main component implicated with P0114 is the engine coolant temperature (ECT) sensor. The ECT is a thermistor (a resistor that changes resistance based on temperature) that measures the temperature of the engine coolant.

Location:

• Usually screwed into a coolant passage in the cylinder head, near the thermostat housing
• Exact location varies, but common areas include the top or back of the engine

Function:

• Sends a coolant temperature signal to the engine control module (ECM)
• The ECM uses this data to adjust fuel injection, ignition timing, variable valve timing, and other parameters
• Ensures optimal performance, fuel economy, and emissions at all operating temperatures

Common Causes

1. Faulty ECT sensor (most common)
2. Wiring issues – damaged wires, loose connections, or short/open circuits[
3. Blown fuse or faulty relay supplying voltage to the sensor
4. Low coolant level causing air pockets around the sensor
5. Using the wrong type of coolant (incompatible with the sensor)
6. Contaminated coolant causing sediment buildup on the sensor

Diagnosis

1. Scan for trouble codes. P0114 should be present, along with any other related codes.
2. Visually inspect the wiring and connector at the ECT sensor. Look for obvious damage, corrosion, or loose pins.
3. Test the resistance of the ECT sensor using a multimeter:
   • Disconnect the sensor and measure the resistance across the pins
   • Compare to the manufacturer's specs at various temperatures
   • At 68°F (20°C), expect around 2,000-3,000 ohms
   • At 176°F (80°C), expect around 200-300 ohms
4. If the readings are out of spec, replace the ECT sensor.
5. If the sensor tests okay, check for voltage and ground at the connector:
   • Key on, engine off (KOEO), should see 5V reference voltage
   • Ohm the sensor ground wire to chassis ground, should be 0 ohms
6. If voltage or ground is missing, trace the wiring back to the ECM and repair as needed.
7. Check the coolant level and condition. Top off if low and replace if contaminated.

Repair and Replacement

• If the ECT sensor is faulty, replace it with an OEM or high-quality aftermarket unit
  • Replacement cost: $30-100 for the part, $50-150 for labor
  • €25-85 for the part, €40-125 for labor
• If wiring is damaged, repair or replace the affected harness
• Flush and refill the cooling system if the coolant is contaminated

Prevention

• Maintain proper coolant level and change coolant at recommended intervals
• Only use the coolant type specified by the manufacturer
• Address any coolant leaks promptly to avoid low coolant conditions
• Avoid aftermarket "performance" ECT sensors, as they can cause drivability issues

Related Codes and Concerns

Other fault codes commonly seen with P0114 include:

• P0115-P0119 (other ECT sensor circuit faults)
• P0125 (insufficient coolant temperature for closed loop fuel control)[
• P0128 (coolant thermostat malfunction)
• P0217 (engine overheating condition)

A faulty or failing ECT sensor can also cause:

• Hard starting
• Poor fuel economy
• Rough running or misfires
• Overheating (in extreme cases)

By understanding the common causes, diagnostic steps, and repair solutions for code P0114, you can quickly resolve ECT sensor issues and keep your engine running optimally. Always consult the factory service information for your specific vehicle to ensure proper repair procedures are followed.

Frequently Asked Questions About P0114 Code

What does the P0114 code mean?

P0114 is a generic OBD-II code that indicates the engine control module (ECM) has detected an intermittent fault in the intake air temperature (IAT) sensor circuit. The signal from the IAT sensor is erratic or alternating between a short and open circuit.

What are the common symptoms of code P0114?

Common symptoms may include:

• Check engine light illuminated
• Engine running in “failsafe” or “limp” mode
• Hard starting, especially when cold
• Rough idle or stalling
• Decreased fuel economy
• Increased emissions

Is it safe to drive with a P0114 code?

You can usually drive safely with a P0114 code for a short distance, but it’s best to diagnose and fix the issue promptly. Driving for extended periods with the engine in failsafe mode may lead to poor performance, carbon buildup, or potential ignition problems.

What causes a P0114 code to set?

Potential causes include:

• Faulty IAT sensor
• Damaged or corroded wiring/connectors in the IAT circuit
• Loose or disconnected IAT sensor connector
• Short to power in the IAT wiring harness
• Faulty engine control module (rare)

How do you diagnose a P0114 code?

Diagnostic steps:

1. Scan for codes and document freeze frame data
2. Clear codes and retest to see if P0114 returns
3. Visually inspect IAT sensor, wiring, and connectors
4. Test IAT circuit for shorts, opens, or high resistance
5. Observe IAT sensor data while wiggle testing the wiring harness
6. Perform pinpoint tests per manufacturer procedures

Can a bad air filter cause code P0114?

A clogged or dirty air filter will not directly set a P0114 code, as this relates to an electrical fault in the IAT sensor circuit. However, a restricted air filter can lead to inaccurate IAT readings and potentially contribute to drivability issues.

Where is the intake air temperature sensor located?

The exact location varies by vehicle, but the IAT sensor is typically located near the air filter housing or intake manifold. It may be integrated into the mass airflow (MAF) sensor housing on some vehicles. Consult your repair manual for the specific location.

How much does it cost to fix code P0114?

The cost to repair a P0114 code depends on the root cause. An IAT sensor replacement typically ranges from $80-$200, including parts and labor. Wiring repairs may cost $100-$300 depending on the extent of the damage. Diagnostic fees are usually $75-$150.

Can I replace the IAT sensor myself?

Replacing the IAT sensor is relatively straightforward on most vehicles, requiring only basic hand tools. However, always consult the factory repair information for the proper procedures, torque specs, and precautions before attempting the repair yourself.

What happens if I ignore a P0114 code?

Ignoring a P0114 code can lead to poor engine performance, increased fuel consumption, higher emissions, and potential long-term damage. The engine may run excessively rich or lean, causing spark plug fouling, catalytic converter damage, or even engine failure in severe cases.

How often should the IAT sensor be replaced?

There is no specific service interval for the IAT sensor. It is designed to last the lifetime of the vehicle under normal conditions. Replacement is only necessary if the sensor fails or becomes damaged.

Can a weak battery cause a P0114 code?

A weak battery alone will not cause a P0114 code, as this points to an intermittent fault in the IAT sensor circuit. However, low system voltage can lead to erratic sensor readings and potentially trigger related codes.

Will disconnecting the battery clear the P0114 code?

Disconnecting the battery will clear the P0114 code from the ECM’s memory, but it will not fix the underlying problem. The code will likely return once the fault is detected again. Proper diagnosis and repair are necessary for a long-term solution.

How does the IAT sensor work?

The IAT sensor is a thermistor that changes resistance based on the temperature of the incoming air. It sends a signal to the ECM to adjust the fuel mixture and ignition timing accordingly. Most sensors have a negative temperature coefficient, meaning their resistance decreases as temperature increases.

What should the IAT sensor resistance be at room temperature?

The exact specifications vary by manufacturer, but most IAT sensors should read between 2,000 to 3,500 ohms at 68°F (20°C). Always refer to the factory service information for the correct values when testing the sensor.

Can a malfunctioning thermostat cause a P0114 code?

A stuck open or closed thermostat will not directly cause a P0114 code, as this relates to the intake air temperature, not the coolant temperature. However, a faulty thermostat can lead to engine running issues that may trigger other temperature-related codes.

Is the IAT sensor the same as the coolant temperature sensor?

No, the IAT sensor measures the temperature of the incoming air, while the coolant temperature sensor measures the temperature of the engine coolant. They are separate sensors with distinct functions.

Can a vacuum leak cause a P0114 code?

A vacuum leak alone will not set a P0114 code, as this points to an electrical issue in the IAT circuit. However, a major vacuum leak can allow unmetered air to enter the engine, potentially skewing the IAT sensor readings and affecting engine performance.

What other codes may be related to P0114?

Related codes may include:

• P0111 – P0113 (IAT sensor circuit faults)
• P0116 – P0119 (ECT sensor circuit faults)
• P0121 – P0124 (TPS circuit faults)
• P0171 – P0175 (fuel trim faults)

Can a P0114 code affect my vehicle’s emissions test?

Yes, a P0114 code can cause your vehicle to fail an emissions test. The IAT sensor directly impacts the air-fuel ratio and ignition timing, which are critical for maintaining low emissions. Always address any diagnostic trouble codes before taking your vehicle for an emissions inspection.