Peugeot 406 Coupe - Fault Code help!

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Sun 25 Mar 2007 21:48
Peugeot 406 Coupe - Fault Code help! - hyperion_blue
I have a 3.0 V6 D9 Peugeot 406 Coupe. It has recently been to Peugeot after repeatedly coming up with "anti-pollution system defective" on the car's radio/information screen, along with Engine management light on the dashboard being lit. I have my own code reader and the code causing this was "P0430 Catalyst System Efficiency Below Threshold (Bank 2)". I cleared the code and it would go away for a week or so and then come back. The odd thing is it passed its emissions test OK at MOT too... It kept doing the above for a while and then started saying "anti-pollution system inoperative" and the car began to run poorly, like it wasn't firing on all cylinders which was confirmed by a code read of "P0303 Cylinder 3 Misfire Detected". I suspected a faulty coil pack (there's one on each cylinder on my model of coupe) and after taking it to a Pug garage they confirmed coil #3 was on the way out and replaced it and the car ran fine with no more faults. Then recently the "anti-pollution system defective" warning has started coming up again = P0430 Catalyst System Efficiency Below Threshold (Bank 2). What does this actually mean, is another coil on the way out, is it something to do with the pre Cat or Cat on bank 2 or a sensor/other fault?!? I really don't want to have to take it back to the pug garage as they charge an arm and a leg!! At the moment the car still runs absolutely fine and I just clear the fault code to put the Engine diagnostic light out for another week or two til it decides to do it again. Anyone giving me a final working solution to this will earn themselves a suitable reward!

Thanks in anticipation

Mark (hyperion_blue)

p.s. I am already a member of www.peugeot406coupe.com and have had no joy from them yet either!
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Sun 25 Mar 2007 22:10
Peugeot 406 Coupe - Fault Code help! - Aprilia
Well, its what it says really. The post-cat O2 sensor signal is indicating that the cat is not converting properly. This could mean that the cat is defective or that the O2 sensor before the cat is faulty, the sensor after the cat is faulty or that there is some other fault (e.g. wiring to the sensors etc). I wouldn't think this indicates a coil problem. I would start by monitoring the sensor signals.
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Wed 18 Apr 2007 22:35
Peugeot 406 Coupe - Fault Code help! - hyperion_blue
Thanks for the tips, in the end the problem worsened and it turned out to be coil #5 on it's way out. A chap on the Coupe club site mentioned that once one goes, the rest seem to go too! In the end I've had all 3 under the manifold replaced, which leaves only 2 not yet replaced. I asked them to keep the two good ones for me so I have these as spares for the front 2 if they start to play up. Just thought I'd post an update which might help other... Cheers
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