P0201 Code: Injector Circuit/Open — Cylinder 1
Quick Answer
The ECU detected a fault in the fuel injector circuit for cylinder 1 — the injector may not be firing or the circuit is open.
At a Glance
What this code means
The fuel injector injects a precise pulse of fuel into the cylinder. P0201 means the ECU detected an open circuit or failure in the injector circuit for cylinder 1. This can mean the injector isn't firing at all, causing a cylinder misfire. It will often appear alongside a P0301 (cylinder 1 misfire) code.
Common causes
- Faulty fuel injector (open internal coil)
- Damaged or corroded injector wiring harness
- Open circuit in the injector power or control wire
- Failed injector driver circuit in the ECU (rare)
- Loose or corroded injector connector
Symptoms you might notice
- Check engine light on
- Cylinder 1 misfire (rough idle, engine shake)
- Possible P0301 misfire code alongside P0201
- Reduced power and fuel economy
- Rough idle especially at cold start
Can you still drive?
With caution and only short distances. A non-firing injector means a constant cylinder misfire, which can damage the catalytic converter.
How serious is this code?
High. A cylinder not receiving fuel runs a constant misfire. Extended driving will destroy the catalytic converter.
Before you replace parts
Parts replacement is often not the first step. Before buying anything, it's worth checking these basics:
- Use a noid light before buying an injector — if the noid light flashes, the circuit is fine and only the injector needs replacement; if it doesn't flash, find the wiring fault first
- Test injector resistance with a multimeter — if it matches spec, the injector coil is intact and the problem is likely wiring or the ECU driver
How to troubleshoot it
- Inspect the cylinder 1 injector connector for damage, corrosion, or disconnection
- Use a noid light — plug it into the injector harness and watch for it to flash when cranking. If it flashes, the circuit is good; replace the injector
- Test injector coil resistance with a multimeter — compare to specification (typically 12–16 ohms). An open circuit (infinite resistance) means a failed injector
- Check for wiring breaks from the injector back to the ECU
- If noid light doesn't flash, trace the wiring fault toward the ECU
Tools that may help
These are the types of tools commonly used when diagnosing this code. Having the right tool can save time and help confirm a diagnosis before spending money on parts.
- Noid light set
- Multimeter
- OBD-II scanner
Estimated repair cost range
Fuel injector replacement (one): $100–$250 for the part. Professional injector service: $150–$350. ECU diagnosis: $100–$200.
Costs vary significantly by vehicle, location, and whether you use OEM or aftermarket parts. These are general ranges for reference only.
When to call a mechanic
If you've completed the basic troubleshooting steps and the code keeps returning, or if you don't have access to the proper diagnostic tools, it's worth consulting a professional. A qualified technician can perform a full diagnosis and confirm the root cause before any parts are purchased. When in doubt, get a professional opinion — it can save you from an expensive misdiagnosis.
Real-world note
The noid light test is the most important diagnostic step for P0201 — it quickly tells you whether the problem is in the circuit (no flash) or the injector itself (flash present, but injector still faulty mechanically).
Informational purposes only. This guide is for educational reference and is not a substitute for diagnosis by a qualified technician. Repair costs, causes, and symptoms may vary by vehicle make, model, year, and condition. Always consult a licensed mechanic before performing major repairs.