P0134 and P0154 Fault Codes - 2003 Honda Accord O2 Sensor Issue
After engine warm-up, one of the oxygen (O2) sensors stops reading on my scan tool, showing a fluctuating equivalence ratio. Shortly after, the second O2 sensor also fails to respond, and the heater control for the sensor shuts down. The O2 sensor on Bank 2 has already been replaced. Anyone experienced this issue or have insights into potential causes?
This behavior suggests a wiring problem between one of the O2 sensors and the other. Check for short circuits in the sensor harnesses. Use a digital multimeter (DVOM) with a wiring diagram to verify that the O2 sensor wires are not grounded or shorted to power. Reference: http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=40962. Always keep your original sensors for reference—only use OEM Honda O2 sensors when replacing.