How To Clear Service Emission System In Duramax Engine

If you had been ignoring the clear service emission system notification on your dashboard, the Duramax engine in your car would hit you with speed restrictions.

What if you need to cover a long distance to reach the nearest auto repair shop? You can get out of this jam if you know how to clear the service emission system message in a Duramax engine.

How To Clear The Service Emission System In Duramax Engine

Unless you are dealing with a faulty sensor or software glitches, the service emission system light usually indicates damage in the emission control system. A car operating with an underperforming emission control system will release a higher amount of pollutants into the air.

Don’t care about that much? The service emission light will still be a headache for you! Modern engines impose speed restrictions when the emission system gets compromised to meet environmental regulations. So, if you don’t act soon, your car will continue to lose speed, and at one point, the speed could lock down at as low as 4 miles per hour.

The diesel particulate filter (DPF), the exhaust gas recirculation (EGR) valve, and the selective catalytic reduction (SCR) system are primary components that make up the emission control system. If you have a problem with the emission control system, one of these parts is likely damaged.

However, inspecting these components is not that simple. You would need time to examine them, and more importantly, you might not have the required level of expertise to check them by yourself. So, try out these tricks to buy yourself some extra time and mileage when the service emission light pops up in the middle of nowhere.

Clearing The Service Emission System In Duramax Engine Without Addressing The Underlying Issue

Method 1. Disconnect The Positive Battery Terminal And Reconnect It

“Have you tried turning it on and off again?” The simplest hack for getting around the service emission restriction is to disconnect the battery’s positive terminal, leave it for a few minutes, and then reconnect it. The message should go away after you turn on the engine. 

This, however, might not work all the time. Even if it does, the message is likely to reappear soon. But, you should be able to check the vehicle by then.

Method 2. Disconnect The Speed Sensor

Disconnecting the speed sensor would be a more effective way to escape the speed limit. Since the engine control unit cannot detect how fast your car is moving without a functional speed sensor, you should be able to drive without restrictions. However, this is no long-term solution either. If you keep on doing this, it could do some serious damage to the engine. 

Having said that, let’s find out how you can do this.

Step 1. Turn Off The Engine

Before starting, make sure you park the car, turn off the engine, and remove the key from the ignition. It’s recommended to disconnect the negative battery terminal for added safety, but it’s not mandatory. A shut-off engine should be enough to get started. 

Step 2. Locate The Speed Sensor

The speed sensor is responsible for measuring the rotation rate of the crankshaft, which allows it to determine the speed of the vehicle. When DEF system restrictions are in place, the engine control unit collects data from the speed sensor and enforces the speed limit restriction. 

Therefore, disconnecting the speed sensor is necessary for overriding the speed limit. If you have a Duramax engine, look at the transfer case to find the on-road speed sensor. If you don’t find it, look at the engine manual or ask your dealer to know where it is.

Step 3. Disconnect The Sensor

The first thing you need to do to disconnect the speed sensor is to find it by following the wiring harness that leads from the transfer case. Then, find the electrical connector that attaches the sensor to the wiring harness. Grip it tightly with your hand and gently pull it away from the sensor until it comes off. 

Make sure to keep the sensor in a safe place where you can easily find it later. Wrap it up in a piece of fabric to protect it from knocks.

Step 4. Start The Vehicle

Start the engine after taking off the speed sensor. The speed limit warning might still show, but it won’t matter since the speed sensor won’t tell the ECU to cut off the speed. If you face problems changing the gear, try shifting to neutral first, and then try moving to different gears. You should be able to do it now.

Again, we must remind you that you should not treat this as a permanent solution to your service emission problem. Driving without a speed sensor is only acceptable for an emergency mileage extension so that you don’t have to walk your way home. Without a speed sensor, your vehicle might experience various performance issues. 

The speedometer, for instance, is likely to show incorrect readings since the car cannot tell for sure how fast you are going. The Anti-lock Braking System (ABS) will become virtually useless as it cannot tell when it should engage and disengage breaks. So, you need to reinstall the speed sensor as early as possible.

Method 3. Clear The Code With A Diagnostic Tool

You can also dodge the restrictions by clearing the codes with a scanner. Clear service emission system messages are not permanent codes, so you can temporarily erase them. They will resurface eventually, but you can expect to drive at least 50 miles before the speed lock returns. So, let’s see how we can do that.

Step 1. Switch Off The Engine

Turn off the engine, but keep the ignition running so that it can power the onboard computer. If the ignition is off, the scanner will not get to access the computer.

Step 2. Hook The Scanner On

Pick up the scanner next. You need an OBD-II scanner that can read and reset codes. It will connect to the OBD-II port that usually sits under the steering column dashboard. If you don’t find it there, look up the OBD-II port location for your vehicle model on the internet. Take a look at the owner’s manual if you have it around.

Step 3. Scan For Codes And Clear Them

Scan the vehicle for codes. You might get error codes like P0401 (insufficient ERG valve flow), P2463 (DPF soot accumulation), or P0420 (Catalyst efficiency below threshold). Clear them with the reset option.

Step 4. Restart The Car

Restart the car now. The speed restriction message should go away. It should come back after you drive for about 50 miles, but that should be enough mileage to get you off the road. In severe emergencies, you can clear the codes every 50 miles using the scanner, but we wouldn’t recommend it unless it’s absolutely necessary.

Final Words

You should learn how to clear the service emission system in Duramax engines only to bail yourself out of emergencies. Make sure to fix the emission control system of your car as soon as you get the chance to avoid fines and potential engine damage.


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