Check engine light with a P3237 code but what is it?
Freeze frame was with engine at 131 F while accelerating.
I changed the glow plug module a few weeks ago.
Dave 2009 e320 bluetec

 

I found that it is related to either fuel pressure (BMW & mini Cooper) or oxygen sensor.
What does it mean on a Mercedes? Can a clogged fuel filter causing pressure error (it's over due for a change -- Dealer has missed changing it.) O2 sensor or Bad exhaust module?

Here's some extract of what I found:

From Mini Cooper and BMW boards
P3237 - Control Module Monitoring Fuel Correction Error

P3237 - DMW, internal fault: Mixture correction factor plausibility monitor

Form https://serviceinformation.lamborghi...b9fde3e3dea638
Open Loop Operation Of UEGO Heater Heating process of the lambda sensor starts, 12 V are applied to the heater and Vs is expected to drop below 1.3V within 6 seconds to allow RpVs reading Vs signal is higher than 1.3V after 6 seconds of heater power at 12V P0135 (or P0155, P3207, P3237 according with which bank is missing) This means that Lamborghini EMS detects if the fuel system is in open loop due to an Heater failure which leads to exceed the required maximum time of 6 sec for the first heating ramp. Fuelling Closed Loop Control - Closed Loop Operation of UEGO Heater – Standard Heater Monitoring Tip temperature is calculated through RpVs and PID heater control is started: RpVs is expected to drop below 140 Ohm (600°C) within 15 secs and continuously monitored not to raise over 140 Ohm for more than 15 seconds. When RpVs < 220 Ohm, closed loop operation starts. RpVs > 220 Ohm (open loop operation) for more than 15 secs P0135 (or P0155, P3207, P3237 according with which bank is missing). 140 Ohm < RpVs < 220 Ohm (still closed loop operation) for more than 15 secs P0135 (or P0155, P3207 P3237 according with which bank is missing). No heater fault detected AND no fuel cut but open loop operation (RpVs < 220 Ohm) for more than 60 secs cumulate during a trip P0134 (or P0154, P3208 P3238 according with which bank is missing). This means that Lamborghini EMS monitors closed and open loop operations continuously

 

Just disconnected battery for ten minutes and reconnected. Code is gone.

 

With a better scanner, it was the old downstream oxygen sensor, a white crust on the tip.
Codes were gone for now.