P0111 OBD-II Trouble Code: IAT sensor circuit range or performance problem

P0111 code definition

Intake Air Temperature (IAT) sensor circuit range or performance problem

What the P0111 code means

P0111 is the OBD-II generic code that indicates the engine control module (ECM) has recorded the IAT sensor input go out of the sensors range or the sensor performance was not as the ECM expected.

What causes the P0111 code?

• The IAT sensor range input to the ECM went to -40°F or 240°F indicating a short or open circuit.

• The IAT sensor input to the ECM is erratic and not giving a steady stable reading.

What are the symptoms of the P0111 code?

• The ECM will turn on the Check Engine Light and go into a failsafe mode.
• The engine may have a hard start condition.
• The engine may also have a reduction in fuel mileage.
• The exhaust may blow black smoke.

Note: The symptoms are determined by the manufacturer failsafe ECM strategy for the vehicle during a failure and may vary between manufacturers and vehicles.

How does a mechanic diagnose the P0111 code?

• The mechanic will need to do a visual inspection to determine any electrical connector, wiring, or sensor issues.

• The technician will scan and document the codes received and view the freeze frame data to see when the code was set.

• The codes should then be reset to clear the OBD-II fault codes and retest the vehicle to see if the code comes back.

• The mechanic will observe the sensor’s live data on the scanner for temperature output to be within specifications.

If no problems are noted, then the next step for the technician to do is to perform a manufacturer's specific pinpoint tests for the code and repair as needed.

Common mistakes when diagnosing the P0111 code

• Not doing a visual inspection first

• Not following the manufacturer pinpoint test procedure step-by-step and skipping steps

• Replacing an IAT sensor before tests indicate a problem

• Before installation of the new IAT sensor, not connecting it and viewing the ECM data to see if the temperature output from the sensor is as expected

How serious is the P0111 code?

• The P0111 code will cause the engine ECM to go into a failsafe mode.

• The failsafe mode may cause excessive fuel consumption, carbon fouling of engine components, and various drive complaints, depending on the manufacturer failsafe mode strategy.

• Driving the vehicle for an extended time with the vehicle in failsafe mode may require additional repairs to remove carbon or repair possible ignition problems.

What repairs can fix the P0111 code?

• Repairing or replacing the IAT connector
• Repairing or replacing the wiring as necessary
• Repositioning the sensor back into the air filter housing or intake air tube
• Replacing the IAT with a new sensor

Additional comments for consideration regarding the P0111 code

• The P0111 code is often associated with P0112, P0113, and P0114 codes.

• Most failures for code P0111 are a harness shorting or a connector corrosion issue.

Need help with a P0111 code?

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