P0201–P0206: injector circuit — when the wire is at fault, not the injector

P0201–P0206 are “Injector Circuit / Open, Cylinder N”, where the last digit is the cylinder number. The numbering logic is regular and covered in DTC structure.

The operative word is Circuit. The control module cannot look inside an injector. It sends a pulse and watches the electrical response. No response produces the code.

Which means the suspect list has three entries: the wire, the connector, and the injector. And the statistics do not favour the injector.

Causes by probability

1. The connector at the injector

The most common. These connectors sit on a hot engine, under the intake manifold, in a vibration zone. The plastic latch ages, contact loosens, the terminal corrodes.

The signature: the code appeared after work in the engine bay. Manifold off, plugs changed, timing job done — and a connector got disturbed.

2. Wiring

Insulation ages from heat, wires chafe against brackets. Rodents also feature — a seasonal classic.

3. The injector winding

Here the injector genuinely is at fault: the winding has gone open or shorted. Test by resistance — typically 12–16 Ω for conventional port injectors, considerably less for direct-injection units.

4. The module’s output stage

Rarest, but it happens — especially after a wiring short that burned the driver.

A ten-minute check

1. Read every code. Several injector codes at once means look at shared supply, not four dead injectors.
2. Check misfire counters per cylinder. Misfires in the same cylinder confirm the injector really is not firing.
3. Measure resistance at the injector connector and compare with other cylinders. A discrepancy points at the injector.
4. Swap injectors between cylinders. The code moved with the injector — it is the injector. The code stayed put — wiring or module.

Step 4 is the most reliable test available, and it is free. It settles the question outright.

How this differs from a dirty injector

People confuse them constantly, and they are unrelated:

	Circuit (P0201)	Contamination
What the module sees	No electrical response	Everything normal
Code	Yes	None
Symptom	Cylinder dead entirely	Rough running, consumption
Fix	Wiring or replacement	Cleaning

A dirty injector produces no codes at all — electrically it is fine. It shows through fuel trims and rough running; covered in rich mixture and lean mixture.

What it risks

A cylinder receiving no fuel misfires continuously. Consequences by severity:

• Noticeable vibration, power loss, P0300.
• Unburnt fuel entering the catalyst. If the injector is stuck open instead, that is a direct route to catalyst overheating.
• Oil dilution by fuel with an injector stuck open.

The same rule applies as for misfires generally: flashing lamp means stop driving. The difference between steady and flashing is covered separately.

Diesels work differently

An important qualification. On common rail diesels the injectors are driven at high voltage, and they carry an extra layer: individual correction codes written into the module at replacement.

So replacing a diesel injector without programming its code produces rough running even with a brand-new part. Covered in common rail injector diagnostics and injector correction values.

In short

• The code is about the electrical circuit, not spray quality.
• The most common cause is the connector, especially after engine bay work.
• Swapping injectors between cylinders settles it outright and for free.
• A dirty injector produces no codes; it is found through fuel trims.
• On diesels, replacement requires programming the correction codes.

Download the app — per-cylinder codes and misfire counters are read with an ELM327 adapter over Bluetooth SPP on Android.