P0201 Code: Cylinder 1 Injector Circuit/Open

OBD-II code P0201 is a generic diagnostic trouble code that is supported in various makes and models and is one of the several listed codes that indicate potential issues in your fuel injector circuits.

What does the P0201 Code Mean?

Diagnostic trouble code (DTC) code P0201 stands for “Cylinder 1 Injector Circuit/Open.” It indicates a potential problem with the #1 Fuel Injector Circuit, like a broken wire, loose terminal, burned out injector coil, or some other circuit interruption issue.

When the injector on an MPI unit is grounded, the injector pintle raises off its seat, and fuel flows during that very brief instant (1-5 milliseconds). When the ground to the injector coil is released, the pintle spring snaps it back against its seat, fuel flow stops, and the collapsing magnetic field induces a spike of about 50 volts that travels back toward the ECM/PCM on that ground trigger circuit, which is designed to handle those voltage spikes.

Once your vehicle’s powertrain control module (PCM) does not detect the expected voltage spike from the #1 injector, it triggers code P0201. Or, if it doesn’t sense 12 volts on the trigger side of the injector (coming through the injector coil from the opposite side), it can use that information to store the code. It varies from OEM to OEM.

Planning a DIY fix for P0201? Read our advanced technical discussion about fuel injection systems.

Continue reading if you want to know the possible causes of P0201.

Note: The definition of Code P0201 may vary depending on the vehicle manufacturer. It is best to consult your trusted repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0201 Code? 

Code P0201 may be triggered due to a number of reasons. Here are some of the possible causes of the code:

• Defective fuel injector
• Circuit issues, such as corroded wiring or poor connections
• An issue with the PCM, such as software in need of an update

What are the Common Symptoms of the P0201 Code?

Here are possible symptoms to watch for:

• Illuminated check engine light
• Engine misfire
• Rough running engine
• Poor fuel economy

How to Diagnose the P0201 Code

Code P0201 has several triggers, and it may sometimes be difficult to determine what is causing this fault. If you are not well-versed with auto repair, it is best to have your vehicle checked by a trusted mechanic or bring your vehicle to an auto repair shop for proper diagnosis.

However, if you have the DIY repair skills and you’re determined to diagnose this code yourself, here are videos to help you understand the code better:

How to Fix the P0201 Code

There is no universal fix for this code. Repair and diagnostic procedures may vary depending on your vehicle’s make and model. For example, the repair steps for P0201 for a Jeep may be different from the repair steps of P0201 on a Mazda.

If you don’t have the proper DIY repair skills, it is best to leave the job to a trusted mechanic. However, if you’re confident you can fix it yourself, you can utilize online auto repair sources and guides to know which repair steps are applicable to your vehicle. To help you, you may also opt to get an ALLDATA single-vehicle subscription.

At In-Depth Look at Fuel Injection

Fuel Injectors have a spring-loaded pintle in the center, which is a thin metal core that only allows fuel to flow through the body of the injector when it (the pintle) is lifted against its spring. Fuel exits the injector in a fine mist. An electromagnetic coil opens the injector whenever the “drivers” in the ECM/PCM are triggered to activate the injector coil. These “drivers” are actually powerful transistors within the ECM/PCM.

On standard MPI fuel injection, the injector is a two-wire circuit, with one side receiving system voltage (+) by way of a relay. The other side of the injector receives a ground pulse from the ECM/PCM, and the length of that pulse each time the injector fires is calculated based on engine load, coolant and air temperature, barometric pressure, and a few other factors. When the throttle is initially opened from idle to part throttle, a few extra injector pulses are added between the regular injector events, because they’re needed at that point to prevent the engine from stumbling (think “accelerator pump” on a carburetor).

The injectors initially fire simultaneously as the engine is spinning, but after the engine starts, the injectors fire following the firing order of the cylinders. The injector delivers its fuel before the intake valve opens on that cylinder and the intake air carries the mist into the cylinder when the valve opens.

The crankshaft sensor determines the cadence of injector firing. As the engine speed increases, so does the speed of the injector pulses, but again, each injector pulse is modified based on load, temperature, etc. The camshaft sensor is used on most platforms to determine which injector to fire first and when each injector should and should not fire based on crankshaft angle and piston stroke.

Gasoline Direct Injection plays by different rules; while the injector is still a two-wire solenoid (except for on some Euro engines with piezo injectors), both the ground side of the injector AND the positive side are operated by the ECM/PCM. The fuel pressure is higher, so a high burst of initial voltage is provided to GDI coil injectors to pop their pintle open against those thousands of pounds of pressure, and the fuel is injected directly into the cylinder rather than being carried into the cylinder by the intake air stream like MPI fuel spray.

Where to Get a New Fuel Injector to Clear the P0201 Code

Daily drives are much more enjoyable when you’ve got an optimized engine. Unfortunately, the same thing can’t be said when a clogged or damaged fuel injector is getting in the way. So, if that’s what triggered the P0201 code, don’t put off replacing it.

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