wwillson
Staff member
I have read many threads on diesel forums about the somewhat problematic TMAP sensor on the L5P Duramax. The sensor sits in the intake and can collect enough soot from the EGR that it can malfunction and cause rough idle and drivability problem or throw a code, which could leave you sitting until you replace the sensor.
There seem to be a couple fixes. One, buy a OEM sensor and keep it and the tools needed in your truck. Two, S&B makes a TMAP sensor spacer that gets the sensor out of the manifold and out of the soot stream.
I purchased an new OEM sensor - GM/ACDelco part #12681993 to have on hand in case I ruined the sensor in the truck trying to clean it and to have a spare on hand if I successfully cleaned the sensor currently in the truck.
Our 2021 Chevy HD Duramax has 17,500 miles, mostly pulling our 20,000 pound 5th wheel. I expected the sensor wouldn't have much soot on it, because the exhaust temperature is usually elevated pulling our trailer.
Tip: The wiring harness connector is impossible to get off, until you figure out the secret. Slide the tab toward the connector, then push down on the tab, it will come right off. I won't tell you how long it took me to get it off the first time.
This is what I found when I pulled the sensor.
This is what the new sensor looks like
The original sensor cleaned up with MAP sensor cleaner and look pretty much like new. There is a TSB from GM that states not to clean the TMAP sensor with MAP sensor cleaner, but I didn't listen. I was careful not to spray the cleaner directly into the port in the base of the sensor where the air pressure sensor is located.
I installed a S&B MAP spacer block and reinstalled the original cleaned TMAP sensor. I took the truck for a drive and all is normal. I didn't notice any difference in the way it sounded or drove. A tip if you install the S&B spacer. Turn the TMAP sensor as you push it into the spacer, it will go right in. If you try to push it in without turning it, you'll be frusty and won't make any progress.
My plan is to pull the sensor in about 5,000 miles to see how much soot is on the sensor.
There seem to be a couple fixes. One, buy a OEM sensor and keep it and the tools needed in your truck. Two, S&B makes a TMAP sensor spacer that gets the sensor out of the manifold and out of the soot stream.
I purchased an new OEM sensor - GM/ACDelco part #12681993 to have on hand in case I ruined the sensor in the truck trying to clean it and to have a spare on hand if I successfully cleaned the sensor currently in the truck.
Our 2021 Chevy HD Duramax has 17,500 miles, mostly pulling our 20,000 pound 5th wheel. I expected the sensor wouldn't have much soot on it, because the exhaust temperature is usually elevated pulling our trailer.
Tip: The wiring harness connector is impossible to get off, until you figure out the secret. Slide the tab toward the connector, then push down on the tab, it will come right off. I won't tell you how long it took me to get it off the first time.
This is what I found when I pulled the sensor.
This is what the new sensor looks like
The original sensor cleaned up with MAP sensor cleaner and look pretty much like new. There is a TSB from GM that states not to clean the TMAP sensor with MAP sensor cleaner, but I didn't listen. I was careful not to spray the cleaner directly into the port in the base of the sensor where the air pressure sensor is located.
I installed a S&B MAP spacer block and reinstalled the original cleaned TMAP sensor. I took the truck for a drive and all is normal. I didn't notice any difference in the way it sounded or drove. A tip if you install the S&B spacer. Turn the TMAP sensor as you push it into the spacer, it will go right in. If you try to push it in without turning it, you'll be frusty and won't make any progress.
My plan is to pull the sensor in about 5,000 miles to see how much soot is on the sensor.
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