2003 Mercury Grand Marquis OBD2 Code P0098 Intake Air Temperature Sensor 2 Circuit High

P0098 code definition

Intake Air Temperature Sensor 2 Circuit High

What the P0098 code means

P0098 is the OBD-II generic code indicating the engine control module (ECM) has determined that the intake air temperature sensor 2 (IAT2) has an open circuit in the sensor circuit.

What causes the P0098 code?

• The intake air temperature sensor 2 has an open circuit in the sensor, connection, or wiring for more than 0.5 seconds during one drive cycle.

• The ECM has an internal open failure of the IAT2 circuit or the connector to the ECM has a problem.

What are the symptoms of the P0098 code?

• The Check Engine Light will come on indicating a problem.

• The engine may hesitate on acceleration.

• The engine may run erratic from being lean or rich depending on outside temperature compared to the ECM sensor input.

How does a mechanic diagnose the P0098 code?

• Visually checks the electrical connections and wire harness to the intake air temperature sensor.

• Clears codes and verifies if the code returns.

• Scans the IAT2 sensor and compares the output to be within specifications compared to the IAT in the mass air sensor to ensure they are within 2° F.

• Shorts the two connector wires together to see if IAT2 temperature readings go above 212° F. This is an indication that the ECM and wiring does not have an open circuit.

• Uses a multimeter to check the resistance of the IAT2 sensor to be within specifications.

• Replaces the sensor if the sensor is showing an open circuit resistance reading compared to sensor specifications.

Common mistakes when diagnosing the P0098 code?

• Not verifying IAT failure by clearing the codes and road testing to see if the problem comes back

• Not following the testing step-by-step to locate the problem within the IAT system

• Replacing parts before conducting thorough pinpoint tests or visual checks

How serious is the P0098 code?

• The engine can hesitate and have a lack of power during acceleration.

• The engine will fail emission testing as long as the Check Engine Light is on and monitors indicate a problem with the IAT system.

• Continued use in a failed state can cause the engine to run too lean or rich depending on outside temperatures.

• The ECM will substitute a 70° F sensor output for the out-of-specification reading for the sensor.

• The engine may run rough or hesitate if the outside temperature is more than 10° F different from the 70° F the ECM uses as a substitute output.

What repairs can fix the P0098 code?

• Replacing the IAT2 sensor if it fails testing

• Repairing or replacing the wiring or connection open circuit to the IAT2 sensor

• Repairing the ECM connector open circuit or replacing the ECM if it failed internally

Additional comments for consideration regarding the P0098 code

The IAT2 code P0098 can be caused from corrosion or a loose connection at the sensor or the ECM. Some sensor failures happen at a certain temperature and if freeze frame data is accessed you may be able to verify when the failure happens to verify the failure.

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