P1139 – OBD-II DTC

OBD-II DTC P1139 – HO2S Transition Time Ratio Sensor 1

DTC P1139 meaning

DTC P1139 refers to a diagnostic trouble code that indicates an issue with the oxygen sensor (HO2S) transition time ratio for Sensor 1. This code is triggered when the Engine Control Module (ECM) detects that the response time of the oxygen sensor is outside the expected range. The oxygen sensor plays a crucial role in monitoring the air-fuel mixture and ensuring optimal engine performance and emissions control.

DTC P1139 symptoms

Common symptoms associated with DTC P1139 may include:

• Check Engine Light illuminated
• Decreased fuel efficiency
• Rough engine idle
• Increased emissions
• Engine performance issues, such as hesitation or stalling

DTC P1139 causes

Several factors can lead to the triggering of DTC P1139, including:

• Faulty oxygen sensor
• Wiring issues or poor connections in the oxygen sensor circuit
• Exhaust leaks affecting sensor readings
• Fuel system problems, such as a clogged fuel filter or failing fuel pump
• Engine management system malfunctions

DTC P1139 seriousness

DTC P1139 can be considered serious as it may indicate a malfunctioning oxygen sensor, which can lead to:

• Poor engine performance
• Increased fuel consumption
• Higher emissions, potentially failing emissions tests
• Long-term engine damage if not addressed

How to diagnose DTC P1139

To diagnose DTC P1139, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P1139 code.
2. Inspect the oxygen sensor and its wiring for any visible damage or corrosion.
3. Check for exhaust leaks that may affect sensor readings.
4. Test the oxygen sensor’s voltage and response time using a multimeter.
5. Examine the fuel system for any issues that could impact the air-fuel mixture.
6. Clear the code and perform a test drive to see if the code reappears.

How to fix DTC P1139 step-by-step instructions

To fix DTC P1139, follow these steps:

1. Identify and repair any wiring issues or poor connections in the oxygen sensor circuit.
2. Replace the faulty oxygen sensor if testing indicates it is not functioning correctly.
3. Fix any exhaust leaks that may be affecting the sensor’s performance.
4. Address any fuel system problems, such as replacing a clogged fuel filter or repairing the fuel pump.
5. Clear the DTC using an OBD-II scanner.
6. Perform a test drive to ensure the issue is resolved and the code does not return.

How to erase DTC P1139

To erase DTC P1139, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the ignition without starting the engine.
3. Access the trouble codes menu on the scanner.
4. Select the option to clear or erase codes.
5. Confirm the action and wait for the scanner to indicate that the codes have been cleared.
6. Disconnect the scanner and start the engine to verify that the Check Engine Light is off.

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