What Does the Engine Code P0203 Mean?

Engine code P0203 refers to an injector circuit issue in cylinder 3.
Written by Tom Hindle
Reviewed by Melanie Reiff
If you come across a P0203 code when you’re inspecting your engine, there’s a problem with cylinder 3 of your injector circuit. That usually means there’s an issue with voltage or resistance in the cylinder or its surrounding parts. Although it doesn’t signal doom for your engine, a P0203 code could make your driving experience a little awkward. 
Diagnostic trouble codes (often referred to as DTCs) pick up specific issues within your vehicle’s engine. As a driver, you’ll often know if something is amiss with your vehicle — especially if a
check engine warning light pops up
. But DTCs can help you diagnose the problem a little quicker, as long as you have an OBD-II code reader. 
The problem is there are a lot of different codes, and they can all get very confusing! That’s why
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has put together everything you need to know about engine codes. Here’s the rundown on P0203. 
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What does the engine code P0203 mean?

Definition: Injector circuit malfunction in cylinder 3
A P0203 code suggests that there’s an issue within the third cylinder of your car’s injector circuit. Most often, the error is picked up due to a change in voltage or resistance around the cylinder, which can ultimately alter how efficiently the engine runs. 

How much will it cost to fix? 

A mechanic usually won’t take too long to find the exact problem associated with a P0203 code, so you’ll probably only pay an hour for labor costs. The exact repair charges depend on what part of the cylinder is broken and how much of the injector circuit needs to be fixed. However, you likely won’t pay more than $150

What can cause the P0203 engine code?

A P0203 code usually flashes in response to a change in voltage or resistance at the third cylinder of your engine’s injector circuit. 
The main culprit for such a change in voltage or resistance is likely the
fuel injector
harness. It’s a wonky wiring system that connects multiple cylinders into your car’s injector circuit. Over time, it can wear down, or some of the cords can become loose. When that happens, the flow of electricity around the circuit can be slightly disrupted—especially around the cylinders. 
But that’s not the only potential culprit for a P0203 engine code. There could be other issues, such as:
  • Faulty fuel injector 3 
  • Poor electrical connection to fuel injector 3 

Common symptoms of the P0203 engine code

Aside from an engine warning light, there aren’t any obvious red flags for a cylinder 3 problem. That said, there are some general engine problems that might point towards a P0203 engine code, such as:
In some vehicles, this problem might be more obvious. Many cars have a fail-safe option that will cut the ignition if something goes wrong within the engine. While that might mean there’s a more significant problem, it could also be a symptom of a cylinder 3 issue. 
Either way, you should always get your car checked out if you suspect something is wrong, especially if you’re concerned about your engine. 

How serious is the P0203 engine code? 

A P0203 engine code isn’t going to spell immediate danger for you or your car. Typically, 0203 codes only bring about minor issues or inconveniences. Your car might take a little longer to start than usual, and you could experience some
—especially from a stop. 
That said, no warning light is ever good. If you see anything flash on your dashboard, you’ll want to act as promptly as possible. Even if you don’t notice anything different about your driving experience, problems can add up over time. While you’re not necessarily seconds away from major engine failure, you could encounter serious problems if you ignore warnings.

Can I fix the P0203 engine code myself?

DTCs are very helpful in identifying problems with your car’s engine. However, just because you can figure out the problem doesn’t mean you can easily solve it. So, unless you’re a professionally trained mechanic, it’s probably best to leave the fixing of cylinder 3 to someone else. 
However, you can expedite the process by identifying your car’s ailment. While a mechanic will likely run their own tests to make sure there are no other major issues, it’s always valuable to be able to know what’s wrong with your car.

Finding insurance for your vehicle 

Once your engine warning light goes off and your P0203 crisis has been averted, you can hit the road safely again. But you shouldn’t go too far without checking in on your
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