What Is the P20E8 Code?
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The definition of code P20E8 is “Reductant Pressure Too Low.” This code simply means that your vehicle’s powertrain control module (PCM) or engine control module (ECM) has detected that the pressure inside the selective catalytic reductor (SCR) system is too low for the manufacturer’s guidelines. You can see this code in many OBD-II vehicles as a generic powertrain code, but the SCR system is only present in diesel engines.
More About Error Code P20E8
Diesel engines tend to have more emissions, primarily from NOx, than gas engines. In an attempt to mitigate the exposure of NOx to the environment, the SCR system was developed. This system uses diesel exhaust fluid (DEF) to convert leftover exhaust particles to nitrogen, carbon dioxide, and water, which are harmless gases. To do this most effectively, the system needs to hold a certain level of pressure so it can inject a precise amount of DEF. The P20E8 code indicates that your system is not holding the correct level of pressure, which can indicate that the system isn’t working as designed.
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What Are the Symptoms of a P20E8 Code?
The symptoms you experience depend on the underlying cause and other components of the vehicle problem. However, the most common symptoms of code P20E8 include the check engine light and other malfunction indicator lamps turning on. This may be the only drivability problem you notice in certain situations, although your vehicle will probably produce more emissions than normal. However, other symptoms include everything from a complete no-start condition to additional codes indicating other problems, and the vehicle going into Limp Mode, a failsafe mode that keeps the engine safer until you can fix the problem.
What Are Some Causes of a P20E8 Code?
Fault code P20E8 can occur for many different reasons. Most of the time, the problem involves part of the system that injects DEF. But many portions of this system can experience a fault. Here are just a few of the common causes:
- Defective, malfunctioning, or faulty injection pump
- Contamination of DEF
- Low reductant fluid level
- A defective or malfunctioning reductant heater element
- Leaks in the pressure feed line
- Leaks in the injection nozzle
- Issues with electrical wiring and/or connectors, including shorted, disconnected, and corroded connector pins
- Programming issues in the reductant injection system control module
- Issues with the PCM
Even very small problems can result in this code, so many of these causes are equally likely.
How Serious Is the P20E8 Code?
The P20E8 code should be treated very seriously. It is true that this problem only concerns exhaust emissions, but malfunctions here can eventually make their way into the catalytic converter, creating catalytic converter failure or even engine damage. Regardless of how serious the P20E8 code is, you should tackle it early for the best and easiest results.
Can I Still Drive with a P20E8 Code?
This code usually doesn’t result in a no-start condition, so you can drive with the code active. You might sometimes experience a no-start condition or a Limp Home failsafe mode, which can severely limit or completely remove your ability to drive the vehicle. However, even if you’re part of the small group with no drivability problems, this problem can still easily progress into catalytic converter failure. You should stop driving when the P20E8 code is active and get help from a qualified mechanic.
How Easy Is It to Diagnose a P20E8 Code?
Due to the many reasons that can cause this code, the P20E8 code can be very difficult to diagnose. Causes can be related to the injection pump, the DEF itself, to the heater element, to the feed line, to the control module, or the wiring, and you need to know how to differentiate all of these. It’s also important that you fix the problem the first time, as follow-up repairs can require you to fix problems you accidentally introduced. Diagnosing a P20E8 code is difficult for DIYers, so it’s best to talk to an expert mechanic instead.
How Difficult Is It to Inspect a P20E8 Code?
The P20E8 code is often difficult to inspect, primarily because this area is not especially common for DIYers to inspect. You may need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle information, such as technical service bulletins and repair guides. You also need a deft hand to avoid creating more problems than you solve, and you should have a wiring guide on hand to check the wiring in the vehicle. This hassle is why it’s often best to talk to an expert.
Need Additional Help with Your P20E8 Code?
The P20E8 code is complex and can cause more problems if you can’t solve it the first time, which is why you might be interested in talking to an expert about the P20E8 code.
To start, you can find an auto repair shop in your area. This ensures you don’t have to drive very far to get assistance.
Additional codes in your code scanner can help you determine the core problem you’re dealing with. The OBD-II database, which you can find at KBB.com, will give you insight into these other codes.
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