03 325xi throwing catalytic converter code and thermostat code. Need opinions.

magnumr2 · 09-27-2011, 12:31 AM

Just recently my 325 has been throwing a code that both cats are operating below effiency but there is also a code stating the thermostat is doing the same thing. My thoughts are that because the thermostat is stuck open the car is not getting to operating temp and is running rich which in turn is making the 02 sensors think that the cats aren't doing their job. I hope its the $76 thermostat and not the $350(a piece) cats. Does this reasoning sound valid?

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Kubica · 09-27-2011, 07:13 AM

Post the actual codes. Prob need a therm and 2 o2 sensors.

AlpinewhiteXi · 09-29-2011, 11:53 AM

If your car is getting to temp quickly and staying there it may just be a $15 thermostat temp sensor. Maybe start there and move up.

magnumr2 · 09-29-2011, 01:26 PM

I don't think it is the sensor because it takes awhile for the engine to get to operating temp and it isn't even operating temp its around 175 F.

tour(ing) de pantz · 10-03-2011, 02:14 AM

both of these things could be coolant temp sensor related. start there.

09-27-2011, 12:31 AM	#1
magnumr2 Registered User Join Date: Sep 2011 Location: akron, oh Posts: 2 My Ride: 03 325xi View My Garage	03 325xi throwing catalytic converter code and thermostat code. Need opinions. Just recently my 325 has been throwing a code that both cats are operating below effiency but there is also a code stating the thermostat is doing the same thing. My thoughts are that because the thermostat is stuck open the car is not getting to operating temp and is running rich which in turn is making the 02 sensors think that the cats aren't doing their job. I hope its the $76 thermostat and not the $350(a piece) cats. Does this reasoning sound valid? Sent from my PC36100 using Bimmer

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09-27-2011, 07:13 AM	#2
Kubica Registered User Join Date: Apr 2008 Location: Boston Posts: 3,908 My Ride: 2003 325xi View My Garage	Post the actual codes. Prob need a therm and 2 o2 sensors.

09-29-2011, 11:53 AM	#3
AlpinewhiteXi Registered User Join Date: Feb 2011 Location: Denver Colorado Posts: 218 My Ride: 01 325Xi // 86 325e View My Garage	If your car is getting to temp quickly and staying there it may just be a $15 thermostat temp sensor. Maybe start there and move up.

09-29-2011, 01:26 PM	#4
magnumr2 Registered User Join Date: Sep 2011 Location: akron, oh Posts: 2 My Ride: 03 325xi View My Garage	I don't think it is the sensor because it takes awhile for the engine to get to operating temp and it isn't even operating temp its around 175 F.

10-03-2011, 02:14 AM	#5
tour(ing) de pantz Registered User Join Date: Jul 2011 Location: Denver, ColoRADo Posts: 16 My Ride: '03 325xiT View My Garage	both of these things could be coolant temp sensor related. start there.