Bad O2 Sensor Draining Gas in Chrysler 300

Had similar issues with my Chrysler 200 (2014). The check engine light triggered due to a failing O2 sensor. The exhaust sensor readings were inconsistent, causing the engine management system to run a rich fuel mixture. The oxygen sensor replacement resolved both the check engine light and restored normal fuel efficiency. The repair was straightforward, just needed to locate and replace the faulty exhaust sensor. In my case, it was the downstream O2 sensor that monitors the catalytic converter efficiency. Before replacing parts, have the mechanic verify which specific O2 sensor is malfunctioning, as these cars have multiple sensors in the exhaust system. They can determine this through proper diagnostic testing. A bad sensor connection or wiring can sometimes cause similar symptoms, so its worth checking the electrical connections first. The repair was not particularly serious or complex, but ignoring it could lead to increased fuel consumption and potential catalytic converter damage over time. After replacement, the engine management system adapted within a few driving cycles and fuel efficiency returned to normal.

Thanks for sharing your experience with the O2 sensor replacement. My Chrysler has now been running great for about 6 months since the repair. The check engine light has stayed off and fuel efficiency is back to normal. Just wondering, what was the total cost for your repair? Also, have you noticed any other issues with the exhaust system since getting it fixed? Would be helpful to know if I should watch out for anything else related to the oxygen sensor down the line.

Good to hear your Chrysler is running better. After taking my car to the mechanic, it turned out the issue wasnt actually a faulty O2 sensor but rather a problematic cable connection to the oxygen sensor. The total repair cost was 95€ to fix the wiring and clean the sensor connections. The air-fuel ratio returned to normal once the connection was properly restored. Since fixing the sensor connection, the exhaust system has worked flawlessly with no check engine lights or other issues. The catalytic converter efficiency readings have remained stable, confirming the repair was successful. Regular diagnostic checks can help catch similar issues early. A properly functioning O2 sensor is crucial for maintaining optimal fuel efficiency and protecting other exhaust components. The initial symptoms you described, increased fuel consumption and warning lights, are classic signs of oxygen sensor issues, whether from the sensor itself or its connections.

UPDATE: After getting several opinions, I finally took my Chrysler to a trusted mechanic. The diagnostic tests confirmed a failing downstream O2 sensor affecting the air-fuel ratio. The total repair cost was 320€ including parts and labor. The mechanic showed me the old oxygen sensor, it was covered in carbon deposits affecting its ability to send proper readings to the engine computer. After replacement, the exhaust system is working perfectly. The check engine light cleared after a few drives and fuel consumption dropped back to normal levels. The catalytic converter also got checked during the repair and thankfully showed no damage from the faulty sensor. Really glad I addressed this quickly before it led to more expensive problems. The whole experience taught me to pay attention to sudden changes in fuel efficiency as they often point to sensor issues. Now 6 months later, everything is still running great with no warning lights or fuel consumption issues. Worth every cent to get it fixed right.