P0201
Injector Circuit/Open - Cylinder 1
If your code reader dashboard displays the generic DTC error code P0201, your vehicle is currently experiencing an active failure related to "Injector Circuit/Open - Cylinder 1". Proper system troubleshooting is required to safely clear this warning.
Driver's Summary
Storing code P0201 is your car's way of telling you something is wrong with the injector circuit/open - cylinder 1. In practice, this fault causes engine misfire, rough idle, lack of power, check engine light. This is a serious fault — avoid extended driving and have your vehicle inspected by a mechanic as soon as possible to prevent further damage.
Symptoms
Engine misfire, rough idle, lack of power, check engine light
Common Causes
- Defective fuel injector on Cylinder 1
- Broken wire to injector
- Unplugged injector connector
- Faulty PCM injector driver
How to Fix
- 1 Test and replace Cylinder 1 fuel injector
- 2 Repair wiring harness break
- 3 Seat injector connector securely
- 4 Test PCM output with noid light
Technical Explanation
The ECM detects code P0201 by continuously monitoring the relevant sensor circuit against calibrated threshold values stored in its non-volatile memory. The PCM monitors crankshaft rotational velocity via the CKP sensor at a resolution of individual tooth gaps on the reluctor ring. A combustion event in each cylinder produces a measurable acceleration spike; its absence or weakness is flagged as a misfire event within a 200-revolution or 1000-revolution test window. The fault remains stored in memory even after the MIL is cleared; it becomes a confirmed DTC after failing two consecutive drive cycles, and the PCM logs a freeze frame record of the engine's exact operating state at the moment of detection.
Is It Safe to Drive?
This fault carries real mechanical risk. The root causes — including defective fuel injector on cylinder 1 — can trigger a chain reaction of component failures if the vehicle continues to be driven. Have it towed or drive directly to a shop without delay.
Mechanic's Pro Tip
Module replacement should always be the last resort for P0201 after exhaustively verifying all power supply circuits, ground connections, and communication bus wiring. Use a wiring diagram to locate all fuses, relays, and ground points for the affected module, and measure voltage drop on each ground with the circuit loaded. A module "failure" is frequently a corroded ground eyelet or a weak battery causing brownout conditions — fix these first and you'll save hundreds of dollars on an unnecessary module replacement.
Fuel injector replacement: $150 - $400