CL500 fault codes showing

[lexman8]

Engine management light on. Logged faults are:

P0130 O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)
P0150 O2 Sensor Circuit Malfunction (Bank 2 Sensor 1)

These 'pending' faults are also showing:

P0136 O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
P0156 O2 Sensor Circuit Malfunction (Bank 2 Sensor 2)

What are 'pending' faults and how do they differ from logged faults?

Am I correct in thinking that 1 faulty sensor could lead to multiple faults being logged? Seems unlikely that 2 or 3 would fail at the same time.

Also, the light came on soon after I floored the accelerator for kick-down (not something I do often). Just a coincidence?

Thanks

 

[E270 Owner]

Pending are faults those that have occurred and then not returned after "x" amount of ignition cycles.

Logged or current codes are those still active or showing an EML fault or in the canbus system.

Stored/pending codes are sometimes left as a record of an ongoing problem until the fault is totally corrected,
sometimes these codes get left uncleared after the fault is corrected and you can end up with a list as long as your arm in MB Star when theres no current fault.

 

[BlackC55]

I would test the live data of the pre-cat O2 sensors. The value should change every one second from a high value to a low value.

 

[Dash1]

As Olly (BlackC55) stated above, it’s referred to as “flip-flop” and the voltage range is between 0.2 volts or 200 millivolts up to 0.9 volts or 900 millivolts - within a one second time duration. The ideal voltage is between 0.4 and 0.5, typically 0.45, which is actually the stoichiometric ratio, or Lambda 1

Regards,

[FONT=&quot]Dash1[/FONT]

 

[lexman8]

Update

Well, after a couple of days normal use with 5 or 6 engine starts the EML went off. Perhaps one of the sensors is on its way out but hopefully it was just a transient problem.

Incidentally, I normally run the car on super unleaded but I had a voucher for 54p per litre off fuel at Morrisons so I filled up with 76 litres of unleaded last time (they don't sell super). I paid 74p per litre, woo-hoo.

I wonder if this is why the EML came on or maybe it's just a coincidence.

 

[jotter22]

Could have been an expensive saving....My lowly 320 only ever gets super.

Tony.