Engine Light!

[Skyliner34]

For the last few weeks the amber engine/malfunction light has came on my dads 2005 k12 1.2S, only done like 11K. Found out using code reader its fault no P0420. We took it for a mot which was due and it failed on emissions. We took the car home and brought new sensors, NTK(NKG) for front and bosch for back oxygen sensor. Fitted them and then took it back and it still failed. Car drove up fine and no malfunction lights. So then they said that they've cleaned a sensor (dunno what sensor) and it finally passed. Fair enough. Drove it home and a few days and it's been ok.

But today the malfunction light has come on again! When we plug in a RAC diagnostic box we get error code P0420 again.

Whats is going on!

thanks

 

[matt1987]

Some suggested steps for troubleshooting a P0420 error code include:

•Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
•Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
•Inspect the downstream heated oxygen sensor (HO2), replace if necessary
•Replace the catalytic converter
One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.


the k12 is know for eating o2 sensors best to take it to nissan i work there so should know some cars have none and some may have 4 or 5, generally it is the rear that plays up but it gives the front at fault.

there was also a thing on an ecu upgrade if the front o2 sensor was changed

like i said best to take to nissan