P1155 – OBD-II DTC

OBD-II DTC P1155 – Lack Of HO2S21 Switch – Adaptive Fuel At Limit

DTC P1155 meaning

DTC P1155 refers to a diagnostic trouble code indicating a lack of signal from the heated oxygen sensor (HO2S) 21, which is part of the vehicle’s adaptive fuel control system. This code suggests that the engine control module (ECM) has detected that the adaptive fuel adjustments are at their limits, meaning the system is unable to achieve the desired air-fuel mixture for optimal engine performance.

DTC P1155 symptoms

Common symptoms associated with DTC P1155 may include:

• Check Engine Light illuminated
• Poor fuel economy
• Rough idling or stalling
• Increased emissions
• Loss of engine power or performance

DTC P1155 causes

Several factors can lead to the triggering of DTC P1155, including:

• Faulty heated oxygen sensor (HO2S) 21
• Wiring issues or poor connections in the sensor circuit
• Exhaust leaks affecting sensor readings
• Faulty engine control module (ECM)
• Fuel delivery issues, such as a clogged fuel filter or failing fuel pump

DTC P1155 seriousness

DTC P1155 is considered a moderate to serious issue. While it may not cause immediate engine failure, it can lead to:

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

How to diagnose DTC P1155

To diagnose DTC P1155, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P1155 code.
2. Inspect the wiring and connectors for HO2S 21 for any signs of damage or corrosion.
3. Check for exhaust leaks that may affect sensor performance.
4. Test the heated oxygen sensor with a multimeter to ensure it is functioning correctly.
5. Examine fuel delivery components for any issues that could affect the air-fuel mixture.
6. Clear the code and perform a test drive to see if the code returns.

How to fix DTC P1155 step-by-step instructions

To fix DTC P1155, follow these steps:

1. Confirm the DTC P1155 is present using an OBD-II scanner.
2. Inspect the wiring and connectors for HO2S 21 repair or replace as necessary.
3. Check for and repair any exhaust leaks that may affect sensor readings.
4. If the sensor is faulty, replace the heated oxygen sensor (HO2S) 21.
5. Inspect and address any fuel delivery issues, such as replacing a clogged fuel filter or faulty fuel pump.
6. Clear the DTC using the OBD-II scanner.
7. Perform a test drive to ensure the issue is resolved and the code does not return.

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