P0201: Injector Circuit/Open - Cylinder 1

What does P0201 mean?

The ECM switches each fuel injector on and off and monitors the circuit. If the circuit for cylinder 1 is open or out of range, it stores P0201. Without fuel, that cylinder misfires.

Both references list a faulty injector and wiring or connector problems as common causes, and say a failed ECM is possible but less common.

Common symptoms

• Check engine light on
• Misfire, often with a cylinder 1 misfire code
• Rough running or reduced power
• Hard starting or stalling in some cases

Common causes

The causes below are the ones commonly seen with P0201. The actual cause can vary by vehicle, engine and mileage, so treat this list as a starting point, not a diagnosis.

• A faulty cylinder 1 fuel injector
• An open or short in the injector wiring
• A poor or corroded connector at the injector
• A faulty ECM (less common)

What to check with a scanner

• Read all codes and look for P0301 or P0300 with P0201.
• Inspect the injector connector for damage, corrosion or a loose fit.
• Read freeze frame data for the conditions when the code set.
• Clear the code and see whether it returns immediately.

How to read and clear P0201 with OBD Master Pro

1. Plug in your adapter. Connect a generic ELM327 (or ELM329) OBD2 adapter to the diagnostic port, usually under the dashboard on the driver's side. Bluetooth Classic, Bluetooth LE, Wi-Fi and USB OTG adapters are supported.
2. Switch the ignition on. Turn the key to ON or start the engine, depending on your car.
3. Connect in OBD Master Pro. Open the app, go to Connection and pick your adapter. Classic Bluetooth adapters connect from the Bluetooth tab, Bluetooth LE adapters from the BLE tab with no pairing needed. Use the generic OBD2 / EOBD profile or your car's brand profile.
4. Read the codes. Open the fault codes screen to see stored, pending and permanent codes. Confirm P0201 is listed and note any other codes, since they often explain the cause.
5. Check the details. Look at freeze frame data, Live data and, where your car supports it, Mode 06 test results (see the checks above).
6. Fix, then clear. After the repair, clear the codes to turn off the check engine light. Clearing also resets the emissions readiness monitors, so drive normally and check the readiness screen before any inspection. Permanent codes cannot be erased with a scan tool; they clear on their own once the car's self test passes.

Tip: you can also look up P0201 and other codes in the app's DTC search without connecting to a car. If your adapter will not connect, use Connection > Share connection log and email it to support. Many cheap ELM327 clones only handle basic engine OBD2, which is all you need for P0201.

When to see a mechanic

Get professional help if any of these apply:

• The check engine light flashes
• The injector needs resistance or circuit testing
• The engine runs very rough or will not start

If you are unsure, a qualified technician can confirm the cause with tests such as smoke testing, pressure testing or scope readings. Clearing a code does not repair the fault.

Related trouble codes

See all OBD2 trouble code guides

Related guides

Check engine light on: what to do · How to read an OBD2 code (P, B, C, U) · Stored, pending and permanent codes and freeze frame · OBD2 readiness monitors explained · OBD2 glossary · OBD2 by car brand