Block Heater Question...
12-16-2014, 04:07 PM
#1
Thread Starter
Join Date: 12-07-2014
Location: Wyo
Posts: 3
Block Heater Question...
Hey Folks,
First-time poster here; be gentle...
Read the following online advice about adding an aftermarket block heater.
(From Block heater on GM vehicles Ricks Free Auto Repair Advice | Automotive Repair Tips and How-To)
I need to add one to my "new" 2009 LT2 2.4L. Have any of you run into this issue??
Block heater on GM vehicles
GM has installed temperature sensing circuitry into the plug on factory installed block heaters. It prevents the heater from operating unless it is colder than 0°F or -18C. It may seem insane, but it really does make sense if you understand why. If you install an aftermarket block heater without this circuitry, the PCM will see warm coolant, but a cold engine and cold air coming into it. Remember, it’s the PCM’s job to determine the correct air/fuel mixture. A cold engine block and cylinder head act as a fire extinguisher when you first start up the engine. So the computer commands a very rich mixture. How does it know what temperature the engine is? It used to look at only the coolant temperature. But now it looks at both coolant temp and the temp of the metal itself. If it see a discrepancy between the two numbers, and the outside air temp coming in through the intake is 0° or above, it assumes there’s something wrong with the coolant temp sensor and sets a trouble code.
Bottom line, if you add an aftermarket heater, it must have the temperature sensing circuitry in it or you WILL set a trouble code. Also, if you ever have to replace the power cord to the factory block heater, you must use a new GM power cable.
Thanks for your input,
Morgan
First-time poster here; be gentle...
Read the following online advice about adding an aftermarket block heater.
(From Block heater on GM vehicles Ricks Free Auto Repair Advice | Automotive Repair Tips and How-To)
I need to add one to my "new" 2009 LT2 2.4L. Have any of you run into this issue??
Block heater on GM vehicles
GM has installed temperature sensing circuitry into the plug on factory installed block heaters. It prevents the heater from operating unless it is colder than 0°F or -18C. It may seem insane, but it really does make sense if you understand why. If you install an aftermarket block heater without this circuitry, the PCM will see warm coolant, but a cold engine and cold air coming into it. Remember, it’s the PCM’s job to determine the correct air/fuel mixture. A cold engine block and cylinder head act as a fire extinguisher when you first start up the engine. So the computer commands a very rich mixture. How does it know what temperature the engine is? It used to look at only the coolant temperature. But now it looks at both coolant temp and the temp of the metal itself. If it see a discrepancy between the two numbers, and the outside air temp coming in through the intake is 0° or above, it assumes there’s something wrong with the coolant temp sensor and sets a trouble code.
Bottom line, if you add an aftermarket heater, it must have the temperature sensing circuitry in it or you WILL set a trouble code. Also, if you ever have to replace the power cord to the factory block heater, you must use a new GM power cable.
Thanks for your input,
Morgan
12-16-2014, 04:25 PM
#2
Administrator
Join Date: 10-13-2011
Location: Welland,Ont Canada
Posts: 37,609
Welcome to the site!
I haven't seen this before, we have an 03 2.2 Sunfire GT it has the factory installed block heater but I have never used it in 11 years we've had the car.
The cord and plug look normal not oversized to accommodate any electronics to sense air temp
I haven't seen this before, we have an 03 2.2 Sunfire GT it has the factory installed block heater but I have never used it in 11 years we've had the car.
The cord and plug look normal not oversized to accommodate any electronics to sense air temp
12-17-2014, 03:56 AM
#3
Senior Member
Join Date: 12-24-2007
Location: Seville. OH
Posts: 2,873
Welcome to the site
I have not seen the hhr's block heaters causing problems.
However I know that the block heater was setting a false code p0116 when the block heater was used.
There is a tsb on this explained that the engine temp sensor and the air intake sensor would not agree on start up when the block heater was used.
The tsb repair was to relocate the engine temp sensor to a different area of the engine away from the block heater.
With all that said it seems possible that GM would have made some changes in there block heaters for the later years.
I have not seen the hhr's block heaters causing problems.
However I know that the block heater was setting a false code p0116 when the block heater was used.
There is a tsb on this explained that the engine temp sensor and the air intake sensor would not agree on start up when the block heater was used.
The tsb repair was to relocate the engine temp sensor to a different area of the engine away from the block heater.
With all that said it seems possible that GM would have made some changes in there block heaters for the later years.
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