My friend brought a peugeot 308 vti and it sems to be really lacking in the power department and it also has the anti polution faulty on the display also has engine management light on, have had it diagnosed by peugeot and they are telling me its the cat ageing but he has had new one fitted a few weeks a go ,its still has code p0420. Any help would be very much appreciated thanks.
i have been reading that the timing chain can stretch which would then give us the low out put on power
would like to try and make sure what is as changing the timing chain is not going to be cheap
thank you for any help
OK, so what does a P0420 code mean anyway?
As mentioned above, the code's description is Catalyst System Efficiency Below Threshold (Bank 1). OK, now tell me that again in plain English please.... let's break it down: the catalyst system being referred to is your three-way catalytic converter; so the catalytic converter is not working properly (i.e. it's not efficient). Bank 1 refers to the side of the engine which contains cylinder #1. On inline engines such as 4 & 5 cylinder engines, there is only one bank. So, to really simply things let's just say that the efficiency of the catalytic converter and/or exhaust pipe and/or O2 sensor is not so great.
There are no symptoms so why should I fix it?
Great question! A P0420 code will cause no symptoms aside from the MIL (malfunction indicator light) will illuminate. The reality is there is still something wrong and your car needs attention in order to be in excellent running condition. A poorly maintained car will run less efficiently, burn more gas, and cost you more money in the long run. Plus, if your check engine light is on for a P0420 code and you decide not to fix it, another more serious code could be triggered and you'd never know. The MIL lights up whether you have one code or ten! While I have your attention, don't forget to do oil changes as the owner's manual schedules and keep those tires inflated to the proper PSI.
So what is causing my P0420 code?
There are a number of things that could be causing this p0420 catalyst efficiency code. The most common thing is the catalytic converter itself is no longer functioning properly. The other likely thing is the rear O2 (oxygen) sensor is no longer working properly. Other things could include exhaust leaks, damaged exhaust pipes, damaged O2 sensor wiring/connectors, plugged catalytic converter, etc.
OK, so I want to diagnose things, what do I do next?
The easiest thing to do first is a visual check of things. Visually inspect the exhaust system for leaks, check the catalytic converter for dents, holes, severe discoloration, and check for a rattle inside. If any of those syptoms are there, the converter likely needs replacement. Then, visually inspect the downstream O2 sensor (behind the converter). Check for broken wires, obvious faults, etc. If all that checks out, you'll want to check the operation of the O2 sensor. To do that, you'll need access to a scan tool or oscilliscope. Check that the waveform is pretty steady. If the reading fluctuates then the sensor is likely bad and will need to be replaced.
On some vehicles such as some Subaru models an ECM reflash will fix the problem. As you can see a P0420 can be caused by many things, so if you have any doubts as to whether you can fix the problem yourself, please seek the advice of a professional technician. Good luck!
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