What are the effects of a faulty rear oxygen sensor on a car?
3 Answers
Engine rear oxygen sensor failure can cause the engine malfunction light to illuminate, and may lead to symptoms such as vehicle shaking with jerking sensations, insufficient power, popping sounds from the exhaust, strong unpleasant odors, car jerking, slow acceleration, inability to reach speed, and increased fuel consumption. Working principle of rear oxygen sensor: The rear oxygen sensor detects the oxygen content in the purified exhaust gas and feeds this information back to the ECU. The computer then compares this data with that from the front oxygen sensor. If the data from the front and rear oxygen sensors are identical (normally the front oxygen sensor signal is greater than the rear), it can be determined that the three-way catalytic converter has failed.
A faulty rear oxygen sensor can cause significant issues. Last time when my car's sensor failed, the engine warning light on the dashboard immediately lit up, and the exhaust fumes became noticeably more pungent. The main problem is that it can't monitor the three-way catalytic converter's working condition anymore, leading to excessive emissions that would definitely fail the annual inspection. Although the car can still run normally, fuel consumption seems to have increased, with a full tank of gas covering dozens of kilometers less. If left unrepaired for a long time, it could even damage the three-way catalytic converter, and replacing that is much more expensive than replacing the sensor. My advice is not to delay when the warning light comes on—go to the repair shop to read the fault code for confirmation and replace it with an original part as soon as possible for peace of mind.
This thing can break and the car will still run, but it's bad for the environment and your wallet. If the catalytic converter efficiency can't be monitored, the exhaust emissions will definitely exceed standards, polluting the environment and being non-eco-friendly. My colleague's car was like this, with fuel consumption inexplicably increasing by about 15%, costing an extra 200 bucks in gas per month. Although there's no noticeable change in driving power, the constant check engine light is annoying. The bigger issue is the catalytic converter might get damaged as a result, leading to repair costs in the tens of thousands. Personally, I think fault code P0420 should be taken seriously, as it affects the vehicle's annual inspection pass rate.
