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Htown_LTZ

Particulate matter sensor

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I have a 2020 silverado with the 3.0 duramax that I purchased Nov 2019 and I bought the module to override the auto start/stop. I've had the check engine light come on 3 times since I bought. The las two were due to a sensor. My question is, could this be related to the module not letting the engine perform a regen? I ask because some guy on YouTube said his truck didn't turn off when he was stopped at the light so he knew it was doing a regen. 

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Cant speak directly.  But I just had mine in for another ECU reprogram due to CEL ...

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In the exhaust you will see 1 sensor that looks like an o2 sensor near the flex joint. There is a TSB on it actually being loose. There is a second sensor that is not visible, but is located on top of the DPF under the body. You can feel it by hand or looking in the gap from the rear of the truck. This sensor was the one that was loose on my truck. The nut itself was still tight. The weld that holds the sensor to the nut was broken, but the design of the sensor keeps it from shooting out due to pressure. Since I couldn’t get easy access to it, I just put copper RTV in place of the weld then after it cured, patched it with high temp JB weld. No more codes, and it has held tight for 10,000 miles including an 800 mile road trip each way. 
Having the dealer replace the sensor is probably the best bet, but dealers around here want to charge for warranty diagnosis, act like they’ve never heard of a loaner vehicle (only $75/day rentals), and want to keep the truck for weeks to replace a sensor. JB weld was cheaper, easier, and probably more durable than a defectively manufactured sensor. Dealer can deal with the future issues when I trade it in.

 

 

The check engine light is probably not from the sensor actually being bad, but from the sensor not providing a consistent reading from wobbling around. The truck uses these 2 sensors and the flow differential between them to determine when a regen is a needed. 

Edited by Sqrls

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There is a (long)  list of things that may prevent auto stop/start from activating. 

 

I find it's not always obvious what is preventing it from doing so.

(although frequently it's because I disabled it ...) 

 

 

FWIW, I've found that I can release the brake enough to get it to restart, with releasing enough that the truck will move. 

After doing that and getting a restarts, it doesn't re-stop until the minimum speed has again been reached. 

I have been at a light with if off, and had it restart before the light changed. (presumably that was the  maximum time timer at work)

 

 

Regen on the 3.0 takes about 10 miles, so its much shorter than either the L5P or the LML. 

I don't think I've been at a stop while in regen -- but imho it would make sense for it not to autostop if regen is active.

 

 

These are the ones listed:

 

Auto Stops may not occur and/or Auto Starts may occur because:
. The climate control settings require the engine to be running to cool or heat the vehicle interior.
. The vehicle battery charge is low.
. The vehicle battery has recently been disconnected.
. Minimum vehicle speed has not been reached since the last Auto Stop.
. The accelerator pedal is pressed.
. The engine or transmission is not at the required operating temperature.
. The outside temperature is not in the required operating range.
. The vehicle is in any gear other than D (Drive).
. Tow/Haul Mode or other driver modes have been selected.
. The vehicle is on a steep hill or grade.
. The driver door has been opened or the driver seat belt has been unbuckled.
. The hood has been opened.

. The Auto Stop has reached the maximum allowed time.

 

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