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Robert, Peugeot Technician
Category: Peugeot
Satisfied Customers: 4716
Experience:  Fully qualified 19+yrs exp/self employed technician in the UK
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I have a 2005 Peugeot 407 SW 2.0 petrol which seems to have

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I have a 2005 Peugeot 407 SW 2.0 petrol which seems to have an intermittent misfire. Not particularly evident at idle, more so when moving when I can feel small dudderings. Has been evident for weeks but put up with it. Then engine management light came on and message 'Anti-pollution faulty' came up. Have replaced plugs and coil pack but no difference though light off and no message. Will now try cleaning injectors (RedX OK?). Any other thoughts welcome as to cure.


Did you scan the car before replacing those the plugs / coil pack?..if so what fault codes was pulled?

Coil pack new or second hand?

What condition wise was the old plugs in?

Customer: replied 3 years ago.

Sorry Robert, all this was done by my friendly mechanic. I dont have this info.

Hi..there thanks for your reply..

Thats fine... But normal practice is to indeed scan the car for fault codes as thats the reason the EML/Anti pollution fail coming up..the antipollution fail means the ecu is see a mixture inbalance/either lean or rich..which can be a missfire due to unburn fuel / or overfuelling fault...using the fault codes can give a better indication as what maybe wrong..considering you had the coil /plugs be more inclined to maybe check the 02,lambda sensors/cat converter..if this missfire has been left for quite a while then this "can" damage the cat converter so bear that in mind..but as above proper testing id say would be the best way forward than spending anymore emissions test/live data test to check lambda sensor/cat performance..i cant really see an injector cause this - because normally if they do go faulty if thats the case then it would still be logged in the ecu as a faulty or come up a single cyl missfire fault,where then you would investigate or swap over injectors to see if the missfire moves to another cylinder confirming a faulty mention that no warnings are up which means it could well be emission related at per possible failed lambda sensor/cat converter..I do hope this helps

Customer: replied 3 years ago.

Thanks Robert - Apparently the error code diagnosed that the coil pack was faulty and was replaced with new.

So if I understand correctly you are saying that the faulty coil pack may have caused the initial misfire and that a rich/lean mixture could have damaged the lambda sensor and/or cat? How could this then result in the same misfire symptoms when the coils and plugs have now been replaced with new?



If the coil was faulty and not providing sufficent spark..this in turn can foul the plugs and cause partial combustion in other words can send unburnt fuel down the exhaust and thus damage the cat converter in the process if left over long period of time..and emission test id say would certainly confirm if the those exhaust sensors are performing aswell as the cat converter itself...if the midssfire is still there..then the fault must be else where and not the coil itself..there so many possibles for missfiring without doing proper diagnoses with the car plugged in/live data and such needs to be montiored..either the faults emissions as i suggested sensors gone or the fault on the ecu itself..which isnt to uncommon for the coil to spike the ecu..but not as common 407 as on the 206 ranges....

Customer: replied 3 years ago.


Can you recommend anywhere in the Gloucester/Stroud/Cirencester/Bristol areas that would be able to carry out these tests?



Best to find someone who has peugeot planet diagnostic software....the best site i can give to search unless you know of a good local indepandant specialist who deals with peugeot/citroen

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