CLK 350 - the story so far and it's all engine

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New Member
Aug 19, 2020
CLK350; Lexus LS400
It has been a while since I last son's CLK350 has been adopted as the family's second car as said son is in London and it is not needed.

My role as mechanic wife drives the Merc and I'm usually restricted to my Lexus LS400 (Year2000 last of that series).

A quick summary of where we are: great car, I love it, it has the AMG pack so sounds great too. As a later car/engine number it is free of the woes that can write off these cars.
Has needed work: fault codes for a couple of the magnets - new ones fitted; water pump, regularly services by me; gearbox service by local independent. I replaced front brakes.
OE parts used and many sourced from MB Newcastle via their website apps.

Recently fitted: new air filters and engine bay located cabin filter.

I noted a few weeks later that the idle was unsteady, a little rough and raised itself and seem to correct itself a few times on warm up. It had changed for sure.
Following this the engine light came on curtailing a journey - luckily not far from home.

Codes PO172 and PO175 showed on the scanner: System too rich Banks 1 & 2 respectively.

The problem with these codes with a basic scanner is they can cover a multitude of components and settings. So I set about checking the basics including the air filters that I'd changed. This what I covered after clearing the codes:

1) Now I had not pushed the bank 1 air ducting hose home on reassembly so possibly airflow was not optimal...must have been distracted...annoyed as I do check stuff...
2) Removed filters - inspected and wondered if they were not of good quality: (this was a departure from OE). Refitted them ensuring manufacturer's badging etc. was to front: I know it shouldn't make a difference but who knows...
3) Paid more attention to the small rear situated gauze holes at either side rear of the air housing using MAF cleaner to clean them.
4) Used MAF cleaner on the central airbox exit to MAF gauze.
5) Removed MAF and using MAF cleaner cleaned the MAF and lower air intake under where the MAF sits.
6) Reassembled double checking fit including ducting. :rolleyes:

All started up and ran fine so I used the car for my modest commute for a few days to check it out. So far so good. But I did not finish there...

There were x2 solenoid magnets that were originals and given that they are prone to go and in order to optimize the engine running etc. I bought x2 for about £60. I had always wanted to do the whole lot in the first place when we had two fail and throw codes in the space of a few months, but the owner had not accepted my choice this time!

Last action was to use Cataclean into the 1/4 of a tank and run the car for 15-20 minutes. I did this on a warmed-up engine. This will clean the fuel and combustion system plus O2 sensors and cat of any aged deposits or new from the run rich experience.

Unless we have an intermittent problem - then all should be well.

The engine runs as it should and is smooth and responsive. Fingers crossed.

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