The powertrain control module detects the low efficiency of the nitrogen oxide catalyst and triggers a code P20EE. Duramax is a V8 diesel engine and mounts on Chevy Silverado and GMC Sierra.
P20EE Code Duramax is a diagnostic code that appears on the OBD II scanners due to a broken NOx sensor of the exhaust, contaminated DEF, and incorrect programming. In addition, malfunctioning filters, faulty SCR injectors, low-grade fluids, and failed selective reduction catalysts cause P20EE.
Their built-in EGR (exhaust gas reticulation) can decrease the toxic levels of nitrogen oxide inside diesel engines. Due to internal faults and failed SCR, the functionality of the catalyst reduces.
What does P20EE Code Duramax mean?
It is a troubleshooting code that indicates the low level of SCR NOx catalyst from the standard threshold. SCR stands for selective catalytic reduction, and NOx is a nitrogen oxide catalyst in the exhaust system of Duramax or diesel engines.
The built-in power control module can monitor and identify the reduced levels of the reactant performance and result in this code. Due to the low efficiency of the NOx reactant, the selective catalytic reduction module fails.
The contaminated fuel enters the emission unit and causes multiple failures. The stability of the SCR is essential because it supports emission with built-in technology.
It injects DEF, which is an automotive-grade liquid with improved efficiency. The catalyst is the passage to transfer the fluid to the exhaust unit.
What are the causes and methods to fix P20EE Code Duramax?
Low-quality diesel exhaust fluid and malfunctioning injectors are significant problems. I have mentioned multiple reasons for this OBD II code.
Broken NOx sensor of the exhaust system
Nitrogen oxide sensors are an essential component of the exhaust systems mounted on the upper side of selective catalytic reduction equipment. It measures the NOx level to optimize the standard efficiency of the emission unit.
The engine cylinders misfire due to excessive utilization and internal heat. Misfiring damages the NOx sensors and decreases the efficiency of injectors.
The engine lacks adequate fuel for lubrication and reduces its function. Check engine light flashes on the dashboard that leads to troubleshooting, and you can find the relevant problem.
To resolve the fault, replace the failed sensor by removing the protective rubber from it. Hold the cables and split them into two portions with a sharp tool.
Select the coded cables, and attach their ends with the divided wires that emerge from the assembly of the NOx sensor. Combine the cords, shrink them with heating gadgets and bind them on soldered spots.
Install the new sensor and attach the wrapped cords to optimize effectiveness.
Metallic dirt and low-quality fuel
A few people accidentally mix the diesel exhaust fluid with low-quality diesel, which reduces its efficiency.
As a result, it cannot support the internal catalyst, decreases its performance from the threshold, and causes P20EE code.
Its quality decreases due to incorrect hoses, nozzles, and pressure pumps. In addition, you cannot purchase DEF from the gas station because it can cause rust.
The metallic pieces of iron, zinc, sodium, and chromium contaminate the DEF. Use high-quality, filtered, and clean DEF without mixing it with any other fluid.
Incorrect programming
The programming of the Duramax system is an upgrade on the trucks, which have built-in advanced diesel engines. It is a specific module to change the DEF flow according to the driving conditions.
Upgrade its level according to climate heat and other hazards. The upgraded system can extend the time of internal procedures to optimize the DEF flow in various components.
Due to human negligence, the limitations alter, which leads to incorrect programming. As a result, it cannot stabilize its flow and produce a P20EE code. Remove the warning with the correct and professional programming of the module.
Excessive leakage of fluid
The exhaust unit undergoes excessive vibrations due to long-distance driving on uneven passages. As a result, it weakens the seals of the equipment.
The seal crack, and the liquid flows in a different compartment. The leakages are dangerous because they reduce the catalyst efficiency. The manifold undergoes more leakage than other components.
Toxic nitrogen oxide enters the cabin and causes suffocation. Stop the leakage by spraying high-quality oil on the bolts of the manifold.
Apply the penetration oil on the flange of tailpipes and connectors, leave for 6 to 8 minutes, and re-tighten the bolts.
The faulty and incompatible selective reduction catalyst
The Duramax emission units have a selective reduction catalyst with a specific chemical reaction. Ammonia is the standard liquid to stabilize the catalytic reactions.
Due to their selective behavior, they cannot deviate from the standard work level. You cannot add ineffective and incompatible catalysts in the exhaust during the modification activities.
They cannot reduce the toxic nitrogen oxide and alters the internal configuration. P20EE code appears with the signs of excessive black smoke from the tailpipes and a sulfur-like odor.
Install selective and compatible options and stabilize their performance to remove the code.
Faulty SCR injectors
The SCR system reduces the emission of nitrogen oxide from the tailpipes by stabilizing the standard performance of the catalyst inside the exhaust of a diesel engine.
The built-in injectors can transfer a sufficient amount of ammonia into the system. However, exceeded ammonia levels lead to abnormal chemical reactions and slip.
The carbon traces cover the injectors and causes rusting. In addition, the clogged injectors cannot perform at their standard threshold, which triggers excessive smoke.
The failed injector cannot shut and open adequately and requires replacement. Remove its external cap and disengage the linkage through pliers to change it.
Pull off the electric wires and connectors, remove the clamp and loosen the injector. For installation, slide a new injector into the cylindrical chamber; readjust the retaining connectors, clamps, wires, and plugs.
A professional mechanic can change them for $342 to $344, and you can complete the task for $195 to $198.
Malfunctioning filters
Duramax has diesel particulate filters that can hold the soot of the exhaust system. In addition, the DE filter can clean the lubricant to maintain the correct emissions.
To reproduce the DEF, they require draining and cleaning after a specific time. Excessive idling, low-grade fuel, and altered operating temperatures can damage the filters, and they cannot purify the DEF and causes the P20EE code.
Due to modified performance, they cannot provide standard efficiency and requires a change. For this procedure, lift the truck with jacks, find the filter and remove the holding screws and bolts with the correct tools.
Adjust the new filter, secure it with bolts, un-lift the truck, and check functionality.
Low-grade fluids in the emission system
You cannot use low-grade or mixed fluid in the emission unit of your Duramax trucks. Due to its low quality, it causes sulfur emission in the engine.
The odor can approach the cabin and causes skin allergies and suffocation. In addition, these lubricants can increase the exhaustion rate through the tailpipes.
Low-grade lubricant triggers the P20EE Code Duramax. You can remove it through a high-grade fluid.
Use DEF, which comprises 30% to 32% urea and 66% filtered water. It is standard for diesel V8 engines without mixing.
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