EdGasket Posted April 14, 2016 Share Posted April 14, 2016 You replaced the cat? If so no point using cataclean as it will still be newish. Cheap aftermarket cats do not work so well as OEM so that may be why the P0420 is getting triggered but its probably good enough for the MoT. You can either fit a standoff for the secondary O2 sensor or put a filter in the wiring; there's a YouTube on how to do that. Cats can cause a bad-egg type smell; doesn't mean there is anything wrong though. BTW where does the secondary O2 sensor plug into? The wire just disapperars through the floor on mine; is it easy to get to the connector? Quote Link to comment Share on other sites More sharing options...
amand Posted April 14, 2016 Author Share Posted April 14, 2016 2 hours ago, EdGasket said: You replaced the cat? If so no point using cataclean as it will still be newish. Cheap aftermarket cats do not work so well as OEM so that may be why the P0420 is getting triggered but its probably good enough for the MoT. You can either fit a standoff for the secondary O2 sensor or put a filter in the wiring; there's a YouTube on how to do that. Cats can cause a bad-egg type smell; doesn't mean there is anything wrong though. BTW where does the secondary O2 sensor plug into? The wire just disapperars through the floor on mine; is it easy to get to the connector? Yes, and to add I had emissions test done today and it passed without issue. All well within limits. So I guess I will try the post O2 sensor. I have no idea where the plug goes for it. :S Will ask mechanic to let me know. Quote Link to comment Share on other sites More sharing options...
EdGasket Posted April 15, 2016 Share Posted April 15, 2016 Hi Aman, I don't think there will be any benefit in replacing the downstream O2 sensor. The Civic is known to be overly sensitive to throwing P0420 codes and an aftermarket cat would probably be enough to upset it. As I said the downstream O2 sensor does not affect the running of the car, it just monitors how well the cat is working in cleaning up emissions. As far as the check light goes, either tape it over, use a standoff on the secondary O2 sensor or a resistor/capacitor filter in the wiring from that sensor. Whoever fitted the cat must know where the electrical connector is for the downstream O2 sensor as they would have had to remove that sensor from the old cat and transfer it to the new cat. How much was the cat from ECP and do you have a part number in case I need one? Quote Link to comment Share on other sites More sharing options...
amand Posted April 15, 2016 Author Share Posted April 15, 2016 Hello Ed, yeah I'm gonna go down the spacer route as the emissions are clean. I understand your point on the sensor. The CAT I got was http://www.carparts4less.co.uk/search/724600030/p/car-parts In terms of the sensor, I think they removed the sensor before removing the CAT but will find out for you. Quote Link to comment Share on other sites More sharing options...
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