AutoCodes – Mercury – P1115 Mercury

P1115 Mercury Code - Intake Air Temperature Sensor 2 Circuit High

Quick Answer

The IAT sensor is a thermistor device in which resistance changes with temperature. Common causes include Faulty Intake Air Temperature Sensor 2, Intake Air Temperature Sensor 2 harness is open or shorted, Intake Air Temperature Sensor 2 circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1115 Mercury indicates Intake Air Temperature Sensor 2 Circuit High.
Common causes: Common causes include Faulty Intake Air Temperature Sensor 2, Intake Air Temperature Sensor 2 harness is open or shorted, Intake Air Temperature Sensor 2 circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,556

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 21, 2019

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P1115 Mercury Description

The IAT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the Powertrain Control Module (PCM) corresponding to temperature.
Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.
The IAT sensor provides air temperature information to the PCM. The PCM uses the air temperature information as a correction factor in the calculation of fuel, spark, and air flow.
The IAT sensor provides a quicker temperature change response time than the ECT or CHT sensor.
Currently there are 2 types of IAT sensors used, a stand alone, non-integrated type and an integrated type. Both types function the same, however the integrated type is incorporated into the mass air flow (MAF) sensor instead of being a stand-alone sensor.

OBDII Code P1115 Mercury - Intake Air Temperature Sensor 2 Circuit High - AutoCodes.com — P1115 Mercury Code - Intake Air Temperature Sensor 2 Circuit High

What does this mean?

What are the Possible Causes of the DTC P1115 Mercury?

Faulty Intake Air Temperature Sensor 2
Intake Air Temperature Sensor 2 harness is open or shorted
Intake Air Temperature Sensor 2 circuit poor electrical connection
Damaged Powertrain Control Module (PCM)

How to Fix the DTC P1115 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor. Monitor the IAT on a scan tool. Look for sudden changes in the reading when the harness is wiggled or the sensor is tapped.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1115 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.