Hi all I just got myself a volvo s40 1.8 petrol. It after throwing up a check engine light followed by engine system service require. I put it in to the obd got 409 bank 1 cat or Sencer. I cleared the light given it full service but engine system service light keeps popping up? Is cat done if so dose it have to be OEM replaced

 

what year? my lookup says the P0409 refers to the exhaust gas recirculation sensor. Usually the cat is tested by the rear O2 sensor.

 

It's a 2008 1.8 SE FLEXIFUEL FFV
Engine Capacity1798
P0420 IS THE CODE SORRY NOT P0409

 

The p0420 is set when the rear o2 sensor exceeds a differential threshold with the front o2 sensor. The possible causes are 1) bad cat (generally they don't go bad without some help like an engine that's consuming oil or coolant - say due to a head gasket or turbo seal) 2) rear o2 sensor 3) intake air leaks or exhaust leaks. I'd start looking around for exhaust leaks - issues with the flex pipe / EGR tube / manifold etc then I'd look for intake air leaks (vacuum lines, cracks in the air tubing, intake manifold seals etc). You can test the O2 sensor(s) - there's two circuits - one's the heating element the other is the actual sensor. You'd need to read up on how to's - but I'd suspect a wonky O2 sensor would throw additiional CEL codes. If you are consuming oil or coolant then that's another problem to deal with but at the end of all the analysis, it could just be time to replace the cat, particularly if the car has high mileage.

 

The clock says 239716k oil levels are good no sign of coolent leak. I check rest over the weekend

 

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