Codes !! What do they mean?

[Mathias74]

Hi everybody

I have some codes popping up and i can erase them but they keep coming back!!

245868 unknown code
P042000 catalyc threshold under value bank 1, permanet
252F00 unknown code
P168900 , solenoid oilpress.regulating, permanent

Can someone please help me understand these codes?
And what i need to do

Regards from sweden
Mathias

[ShadeTek]

What version of car do you have? Where are you reading these codes from?

[Dancake]

P0420 - This means that your catalytic converter isn't working as intended. The fault code is determined by the monitoring of the pre and post cat lambda sensors. Typically the fault is stored if the post-cat lambda sensor detects more unburned oxygen than it expects to find at a given engine temperature or load.

This doesn't necessarily indicate a faulty catalytic converter. There are a few things that can influence the readings of the lambda sensors. These are as follows-

- Misfires (coil packs, HT leads, spark plugs, compression, valve leakage, faulty injector pulse etc)
- Fuelling (faulty injectors for example)
- Air leaks (Both from the intake system and the exhaust system)
- Faulty lambda sensors or wiring

You also need to look at live data to investigate the operation of your lambda sensors to see if they are switching properly. Very cold temperatures can also have an affect on catalytic converter efficiency.

Regarding the other codes, the description you give for P1689 doesn't match any that I can cross reference it to, and unknown codes are often nothing of significance. What type of code reader are you using, as sometimes aftermarket code readers generate false codes that have nothing to do with the actual fault.

[Tatsfield]

+1 with Dancake, but sadly it often does mean that the catalyser is operating below the acceptance threshold.

In a previous life I ran V6 Peugeot 406 coupes which have front and rear bank catalysers which are monitored for the self testing anti pollution system. If they show warning lights, the car fails the MoT and the Peugeots were notorious for eating their catalysers. Dodgy injectors or ignition coils dumping excess unburnt fuel into the exhaust system poisoned the cats and they threw P0420 and P0430 faults (front and rear bank) which were usually not recoverable. With old low value cars, this represents an economic write-off so desperate measures were called for. The illegal addition of extension mounting tubes to the lambdas, withdrawing the sensor tips from the main gas stream, stopped the warnings and enabled cars to pass the MoT and live on. Very reprehensible but understandable behavior from owners besotted with their rare Italian made GT cars. So now you know.