Alfa MiTo O2 Sensor Failure Draining Gas Tank Fast

Had the same issue with my Alfa Giulietta 1.4T last year. The check engine light came on and the malfunction indicator showed the oxygen sensor heater circuit problem. The symptoms matched exactly, increased fuel consumption and inconsistent air-fuel ratio readings. The root cause was a damaged wire connection at the oxygen sensor plug, not the sensor itself. The connector had corroded due to heat exposure from the exhaust system. The car components were fine, but the wiring needed attention. This is typically not a major repair when caught early. If left unaddressed, it can lead to catalytic converter damage due to improper fuel mixture. The repair involved cleaning the connector pins and replacing the wiring harness section connected to the sensor. Good catch on noticing the fuel consumption increase, this is a clear indicator something was off with the air-fuel ratio management. Worth getting it fixed soon, as poor sensor readings can cause long-term engine performance issues and might affect your next emissions test. The fix took about 2 hours at the garage. Consider asking them to check both upstream and downstream sensors while they are at it, since they fulfill different monitoring functions.

Thanks for sharing your experience with the Giulietta. Had a similar oxygen sensor issue with my MiTo and the faulty sensor symptoms were identical, the check engine light would not go away and fuel economy was terrible. The mechanic found the upstream sensor had failed completely, requiring a full replacement rather than just a wiring fix. The air-fuel ratio was way off, causing the engine to run rich. Did you notice any other issues after the repair? Would be helpful to know if you remember the final cost, my repair bill felt a bit steep at 280 Euro for parts and labor.

Had the car checked by my mechanic last week and wanted to follow up. The oxygen sensor heater failure was resolved, turned out to be exactly what I suspected, just a faulty connection at the sensor plug. Total repair cost was 95 Euro, which seems reasonable compared to your full sensor replacement. Since fixing the wiring connection, the check engine light has stayed off and fuel consumption is back to normal levels. The exhaust system is performing properly now that the sensor gets correct voltage through the heater element. No additional issues have appeared after the repair. The mechanic confirmed through sensor testing that both upstream and downstream oxygen sensors are functioning correctly now. Much cheaper fix than replacing the entire component. Your case sounds like it progressed further, explaining the higher cost for the complete sensor replacement. Getting the wiring sorted early probably saved me from more extensive damage and higher repair costs down the line. These sensor circuit issues can really impact engine performance if left unchecked.

Just visited my mechanic today to get everything sorted out. The wiring connection to the oxygen sensor was completely corroded and needed replacement. Mechanic showed me the damaged parts, the heat from the exhaust had really done a number on those connections over time. Repair took about an hour and set me back 150 Euro including parts and labor. Much better than expected after seeing your full sensor replacement cost. The check engine light turned off right after the fix and a quick test drive showed the engine running smoother already. Really glad I caught this early before the faulty sensor caused more serious issues. The car components all checked out fine during inspection and sensor testing confirmed everything is working properly now. Fuel consumption has already improved on my drive home from the shop. Looks like catching these oxygen sensor problems early really makes a difference in both repair costs and preventing further damage.