P2001 NOx Trap Efficiency Below Threshold Bank 2
Content
P2001 NOx Trap Efficiency Below Threshold Bank 2
OBD-II DTC Datasheet
NOx Capture Efficiency Below Threshold, Bank 2
What does this mean?
This Diagnostic Trouble Code (DTC) is a generic transmission code, which means it applies to all 1996 vehicles (Nissan, Honda, Infiniti, Ford, Dodge, Acura, Toyota, etc.). Although general in nature, the specific repair steps may differ depending on the brand / model.
A stored P2001 means the powertrain control module (PCM) has detected a nitrogen oxide (NOx) level that exceeds the programmed limit. Bank 2 refers to the side of the engine that does not contain cylinder # 1.
The combustion engine emits NOx as exhaust gas. Catalytic converter systems, which are used to reduce NOx emissions in gas-fueled engines, are less efficient in diesel engines. This is due to the higher oxygen content in the exhaust gases of diesel engines. As a secondary method for NOx recovery in diesel engines, a NOx trap or NOx adsorption system must be used. Diesel vehicles use Selective Catalytic Reduction (SCR) systems, of which a NOx trap is part.
Zeolite is used to trap NOx molecules to prevent them from being released into the atmosphere. A web of zeolite compounds is anchored inside a housing that looks like a catalytic converter. Exhaust gases pass through the canvas and NOx remains inside.
To renew the structure of the zeolite, flammable or flammable chemicals are injected through an electronically controlled injection system. Various chemicals have been used for this purpose, but diesel is the most practical.
In SCRs, NOx sensors are used in the same way as oxygen sensors in gasoline engines, but they do not affect the fuel adaptation strategy. They monitor NOx particles instead of oxygen levels. The PCM monitors the data from the NOx sensors before and after the catalyst to calculate the NOx recovery efficiency. This data is also used in the delivery strategy of the liquid NOx reductant.
The reduction agent is injected using an injector that is electronically controlled from either the PCM or the SCR module. The remote reservoir contains liquid NOx reductant / diesel; it resembles a small fuel tank. The reductant pressure is generated by an electronically controlled fuel pump.
If the PCM detects a NOx level above the programmed limit for bank 2, a P2001 code will be stored and the malfunction indicator lamp may illuminate.
symptoms
Symptoms of a P2001 code may include:
- Excessive smoke from engine exhaust
- Reduced overall engine performance
- Increased engine temperature
- Reduced fuel efficiency
reasons
Possible causes of this engine code include:
- Defective or overloaded NOx trap or NOx trap element
- Defective diesel exhaust fluid injection system
- Inappropriate or unsuitable NOx reducing fluid
- Inoperative exhaust gas recirculation system
- Severe exhaust gas leak in front of NOx trap
Diagnostic and repair procedures
A good starting point is always to check the Technical Service Bulletins (TSB) for your particular vehicle. Your problem may be a known issue with a known manufacturer-released fix and could save you time and money while troubleshooting.
To diagnose the P2001 code, you will need a diagnostic scanner, a digital volt / ohmmeter (DVOM), and a vehicle information source such as All Data (DIY).
I would start by visually inspecting all the wiring harnesses and connectors in the system. Focus on wiring close to hot exhaust system components and sharp exhaust shields, especially on Block 2.
Check the exhaust system for leaks and repair if necessary.
Make sure the SCR tank contains reductant and is of the correct quality. Follow the manufacturer's recommendations when adding reducing fluid.
Check the operation of the exhaust gas recirculation (EGR) system with a scanner. Restore all stored EGR codes before attempting to diagnose this code.
Retrieve all stored DTCs and freeze frame data by connecting the scanner to the vehicle's diagnostic port. Write down this information; this can be helpful in diagnosing intermittent code. Clear the codes from the system and start the engine. I would let the engine reach normal operating temperature and test drive the car to see if the code is cleared.
If it is reset, plug in the scanner and observe the NOx sensor data. Narrow your data stream to include only relevant data and you will get much more accurate information.
If any of the NOx sensors are not working, check for a blown fuse in the engine compartment or under the dashboard. Most NOx sensors are of a 4-wire design with a power wire, a ground wire, and 2-signal wires. Use DVOM and service manual (or all data) to check battery voltage and ground signals. Check the sensor output signal on the engine at normal operating temperature and at idle speed.
Additional diagnostic notes:
- The wrong choice or lack of anti-aging fluid is the most common reason for the code P2001 to be stored.
- Eliminating the EGR valve is often the reason for the ineffectiveness of the NOx trap.
- High performance aftermarket exhaust system components can also lead to storage P2001
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NOTE. This information is provided for informational purposes only. It is not intended to be used as a repair recommendation and we are not responsible for any action you take on any vehicle. All information on this site is protected by copyright.
