EML after using STP Complete Fuel System Cleaner.

[ringway]

Hi Chaps.

I had the engine management light on my E430 and needed a new Lambda Sensor. Had that fitted and all was ok apart from a minor misfire at idle.

A week later I added some STP Complete Fuel System Cleaner and the misfire has diminished but now the EML is back.
Could the STP be causing the ECU to think the engine is running to rich, or do one of the other 3 02 sensors need replacing? I hope it's not a CAT.
I plan to run off the fuel that contains the additive and see if the EML remains with the addition of un-dosed fuel.

Either way, the code will be stored and the EML will remain, but any thoughts on this would be helpful. STP Complete Fuel System Cleaner. LINK.


TIA.


Paul.

 

[flango]

Not sure on STP but we used to use loads of Forte system cleaner which I suspect is similar and never saw an issue. Have you checked the new value from the O2 sensor to make sure its working OK, I've had this before fitted new O2 sensors and they were faulty. Think you can get the live data from STAR, symptoms point to O2 sensor or CAT, but don't panic CATs are cheap these days with depressed PGM metal prices

 

[ringway]

Good points, Ian.

Yes, the car will have to go on Star. One thing that springs to mind is that when ECP sent the sensor it gave a bad reading. The garage checked the box and ECP had sent the wrong sensor. Fitted new Bosch sensor and all was well (at least EML-wise) until the day after I added the STP.

Likewise, I have never had any issues with additives. My diesels run on Millers and I have used Forte with success in the past. Also the BG 244 really pepped up my Sprinter at around 160k. There's always a bottle or two of Redex in the garage to.