I’m looking for technical help or recommendations on EML Light
Hi, I am having trouble with an EML on my dash. I have OBD2 code P0420 (Catalyst System Efficiency Below Threshold (Bank1)). I can’t figure out the cause. I’ve had both O2 sensors replaced with brand new parts. The exhaust is less than a year old (with a sports cat). What would people look at next?
Is it also true that the car needs to be mapped to avoid an EML when going with a different exhaust setup?
First check that the sensors are both receiving power from the battery both +and - leads, than check the sensor resistance and lead not grounded or open circuit.
After that exhaust leaks.
Do you have a recent MOT Emission test result? Not Pass / Fail but the actual readings?
Edit: Nevermind, it seems like the voltage should just range between 0 and 1 from my understanding. I still have to check the voltage of the other sensor over time.
I will get my electrician on it. However, using OBD2, I found the following which I suspect is not normal:
0 voltage on startup for O2 Sensor 1 and over a period of 3 minutes, climbs only to 0.43V.
