What Is the P203B Code?
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The P203B code definition is “Reductant Level Sensor A Circuit Range/Performance.” This code indicates that your powertrain control module (PCM) or engine control module (ECM) has identified a problem with the electrical current that is delivered to your vehicle’s reductant level sensor, whichever is indicated as sensor “A.” This code doesn’t necessarily mean that there’s something wrong with the sensor or reductant level, just that the circuit is delivering a reference voltage outside of general manufacturer levels. As a generic powertrain code, this code can show up in any diesel engine that has a reductant level sensor.
You may also be interested in P203F — Reductant Level Too Low.
More About the P203B Code
In a diesel engine, leftover exhaust particles within the engine need to be converted into harmless gases. To do this, your exhaust system temperature increases, and then diesel exhaust fluid (DEF) is injected into the exhaust stream, increasing the temperature of the diesel particulate filter and converting the gases to harmless particles. If there is any nitrous oxide (NOx) left, the reductant catalyst (SRC) helps reduce it. The reductant level sensor helps your engine control module measure the exact fluid level in your DEF storage tank so it can make sure it’s using the DEF correctly. The P203B code indicates that the electrical connection between the DEF tank and the ECM is giving an incorrect voltage measurement.
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What Are the Symptoms of a P203B Code?
As with many diagnostic trouble codes, the most common symptom of the P203B code is the check engine light turning on. In many cases, there may not be any further symptoms than just your check engine light. However, if there are more symptoms, they could include excessive smoke from your exhaust, a fluctuating DEF fluid level reading, or general issues with readings from your reductant tank level that aren’t accurate. Additionally, in most cases, you won’t pass an emissions test with this code.
What Are Some Causes of a P203B Code?
A faulty DEF level sensor is usually the most common cause of this code. However, issues with your reductant level sensor circuit, including general electrical issues, can also result in the code. Occasionally, if you’ve accidentally put the wrong fluid in your DEF storage tank, it could also impact resistance levels. Finally, problems with mechanical obstruction of the sensor level arm inside the storage tank can also result in this code.
How Serious Is the P203B Code?
The P203B code can be serious, but for different reasons than you might think. This fault code very rarely has any impact on drivability, and it may not even impact your vehicle’s fuel economy. However, although it may seem like a minor code, your discrete level sensor impacts your exhaust emissions, which can cause you to fail emissions tests and can eventually move to more “serious” engine codes. If you’re dealing with issues surrounding vehicle emissions, you should fix the problem, even if the active codes don’t seem to be a big deal.
Can I Still Drive with a P203B Code?
You can almost always drive with the P203B code active. This error code doesn’t have a huge impact on your vehicle; the primary component wiring issues could have to do with your emissions system, not most driving systems. While DEF fluid is important, it doesn’t usually impact whether or not your vehicle can drive. However, you should avoid driving with this range code active. Any codes can eventually develop into more serious ones, as problems with calculating any component of your engine can eventually develop into a more severe engine problem overall.
How Easy Is It to Diagnose a P203B Code?
The diagnostic steps for the P203B code can be fairly straightforward, but it’s important to use a code reader to rule out certain issues before you diagnose the code. Running through vehicle diagnostic components can be difficult for a DIYer; even in OBD-II vehicles, the specific process to fix different issues will vary depending on the individual issue. You may need to check technical service bulletins, run through diagnostic flowcharts, and understand where the most common issues are in your specific vehicle. This is why it’s very common to get help from an expert instead of trying to diagnose the P203B code yourself.
How Difficult Is It to Inspect a P203B Code?
It can be just as difficult to inspect the P203B code as it can be to diagnose it. Inspecting the code also requires you to have a fairly complete understanding of exhaust system components; you’re unlikely to be able to get the information you need by just knowing the basic steps. Plus, you need to personalize these inspection steps to your specific vehicle make and model. If you’re worried about being able to fix your diesel engine, it’s definitely best to just talk to an expert.
Need Additional Help with Your P203B Code?
If you need extra help with the P203B code, you’re not alone. This is a very common issue that many people end up needing assistance from an expert with.
First, you should try to find an auto repair shop in your area. While this can be most important for codes that have severe interactions with drivability, the ease of access for a local auto repair shop can be important regardless.
You may also want to check out the OBD-II database at KBB.com. This database will give you more insight into the codes within your vehicle, allowing you to understand what’s likely to need fixing before you even leave.
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