Subaru Legacy 2002 Petrol P0130 Fault: O2 Sensor Bank 1 Circuit Malfunction Diagnosis and Repair Cost Advice
I'm experiencing a P0130 diagnostic code on my 2002 Subaru Legacy petrol engine. The error indicates a malfunction in the Heat Oxygen Sensor (HO2S) for Bank 1. Common causes include heating element failure, poor electrical connections, or wiring issues. Another potential cause is a fault in the O2 sensor signal to the ECM. The local garage has quoted £300 for the replacement part and an additional £350 for labor. Since this is my sister's car and she has no automotive knowledge, I'm concerned about being overcharged. In my experience from aircraft engineering—where monitoring systems often fail rather than the actual components—I suspect that the issue may lie in the sensor circuit or wiring, not necessarily the sensor itself. I'd appreciate any practical troubleshooting tips or advice on how to verify the fault before replacing parts. Is it worth checking voltage, ground connections, and fuses first? Any guidance on cost-effective diagnostics would be very helpful.
The most likely culprit is the O2 sensor located in Bank 1 Sensor 1. However, before replacing the sensor, it's essential to check all wiring and electrical connections for proper voltage, ground continuity, and ensure that the relevant fuses are intact. A faulty connection or short circuit could be mimicking a sensor failure.