PO Code 0300 and PO Code 0141

Yorkshire GOC · 30th December 2020, 12:23

Just done 125 miles today - car ran fine - however on occasion i felt a really slight hesitation which i put down to my imagination at the time.

Anyway nearing home the Check Engine light started flashing for about 20 seconds. Put my code reader on the car and got

PO 0300 multiple misfires (albeit very very slight)

PO 0141 O2 Sensor Heater Circuit Malfunction Bank 1 sensor left.

So i assume one of my 02 Lambda sensors is playing up and causing a slight misfire? Fuel consumption is OK.

COLVERT · 30th December 2020, 14:03

I believe that if one plug is not firing correctly the O2 sensor will pick up more unburnt O2 in the exhaust.--( The sensor just doing its job. )

Yorkshire GOC · 30th December 2020, 14:41

Searching on the MG Rover site from a few years back this was the answer given for these codes.

These are both fault codes from a faulty lambda probe. Second probe is expecting certain readings as determined by faulty probe but they don't match, faulty probe is giving the same incorrect readings to ecu, ecu corrects fuelling accordingly, this causes misfire.

30th December 2020, 12:23	#1
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,063 Thanks: 1,842 Thanked 623 Times in 469 Posts	PO Code 0300 and PO Code 0141 Just done 125 miles today - car ran fine - however on occasion i felt a really slight hesitation which i put down to my imagination at the time. Anyway nearing home the Check Engine light started flashing for about 20 seconds. Put my code reader on the car and got PO 0300 multiple misfires (albeit very very slight) PO 0141 O2 Sensor Heater Circuit Malfunction Bank 1 sensor left. So i assume one of my 02 Lambda sensors is playing up and causing a slight misfire? Fuel consumption is OK. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

30th December 2020, 14:41	#3
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,063 Thanks: 1,842 Thanked 623 Times in 469 Posts	Searching on the MG Rover site from a few years back this was the answer given for these codes. These are both fault codes from a faulty lambda probe. Second probe is expecting certain readings as determined by faulty probe but they don't match, faulty probe is giving the same incorrect readings to ecu, ecu corrects fuelling accordingly, this causes misfire. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

30th December 2020, 14:03	#2
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	I believe that if one plug is not firing correctly the O2 sensor will pick up more unburnt O2 in the exhaust.--( The sensor just doing its job. )