A catalytic converter is built to last a long time. So when one fails on an RLX, it's usually a sign of something else going wrong, not just bad luck. Before anyone bolts on an expensive new converter, the real question is what killed the old one. Here's how to read it.
What the Code Actually Means
A failing converter almost always shows up as a check engine light with a P0420, which says the converter isn't cleaning the exhaust the way it should. That code is a starting point, not a verdict. A lazy oxygen sensor throws the same code without the converter being bad at all. So the first job is figuring out whether the converter truly failed or a sensor is lying about it.
Why It Failed
A converter rarely dies on its own. Something upstream usually took it out, and if you skip that part, the new one fails too:
- An engine burning oil, which coats and clogs the honeycomb inside
- Misfires sending raw fuel into the exhaust, which overheats it
- A coolant leak into a cylinder, which poisons the catalyst
- A rich fuel condition running too much gas through it
Find and fix the cause, or you're buying converters twice.
What You Might Notice
Beyond the dash light, a plugged converter shows itself. You feel a drop in power and worse mileage as it chokes the exhaust. A sulfur, rotten-egg smell can drift from the tailpipe. A rattle underneath can mean the honeycomb broke apart. Badly clogged, it can put the RLX into limp mode, and that's the late stage you'd rather catch before it gets there.
Why the Diagnosis Comes First
Converters are pricey parts, more so on an Acura V6. That's exactly why guessing is the wrong move. We test the converter's actual efficiency and check the oxygen sensors before calling it, then look for the upstream cause so the new one isn't set up to fail. An honest diagnosis here can save you from paying twice.
How We Check It
When an RLX comes in with a converter code, we read the codes and the live sensor data to see how the converter is really performing. We compare the upstream and downstream oxygen sensor behavior. We look for the misfires, oil burning, or leaks that take converters out. Then you get the straight answer and the cost before anything gets replaced.
Get a Real Answer First
A converter code is worth understanding before you spend on the part. Bring your RLX to Driven Auto Care of Castro Valley and we'll test the converter, check the sensors, and find the real cause. Call to set up an exhaust diagnostic.
