P0262 on the 7.3L Power Stroke is a cylinder 1 injector circuit high fault. The 7.3L uses HEUI injectors driven by the injector driver module (IDM), which sends high-voltage pulses through the under-valve-cover connectors and harness to each injector solenoid. P0262 means the module saw the cylinder 1 injector control circuit reading high, pointing to an open circuit, a short to voltage, or a solenoid that is not completing the circuit correctly.
The 7.3L is a durable engine, but its injector power passes through connectors under the valve cover that suffer from oil, heat, and age. A single-cylinder code like P0262 narrows the diagnosis to the cylinder 1 circuit, which speeds up the repair. The cause is usually a connector or wiring problem rather than a failed injector, so confirm the electrical path before replacing parts.
What P0262 means
The IDM drives each injector solenoid and monitors the circuit. P0262 sets when the cylinder 1 control circuit reads high, which typically indicates an open connection, a break in the wiring, or a short to a voltage source. It is an electrical fault code that directs you to the under-valve-cover connector, the wiring, and the cylinder 1 solenoid rather than to internal injector wear.
Common causes
- Open or corroded under-valve-cover connector on cylinder 1
- Broken or chafed injector wiring
- Failed cylinder 1 injector solenoid reading open
- Short to voltage in the injector control circuit
- Oil intrusion degrading the connector pins
Symptoms
- Misfire or dead cylinder on cylinder 1
- Rough idle and reduced power
- Hard starting, particularly when hot
- Check engine light with P0262 stored
- Smoke from incomplete combustion
How to diagnose it
Perform an injector buzz test and listen for a response on cylinder 1; no click points to an open circuit or a failed solenoid. Inspect the under-valve-cover connector and the valve cover harness for oil, corrosion, and cracked insulation, since these degrade with age on the 7.3L. Measure the cylinder 1 solenoid resistance and check the wiring from the IDM for an open or a short to voltage. Confirm the under-valve-cover connector is fully seated and its pins are clean.
How to fix it
Repair broken or chafed wiring and clean or replace the corroded under-valve-cover connector first, as these are the most common causes of a single-cylinder high circuit fault. Reseat the connector and confirm clean pins. If the wiring checks good but the cylinder 1 solenoid reads open, replace that injector. After the repair, clear the code, confirm cylinder 1 responds in a buzz test, and road test. For under-valve-cover connectors, harnesses, and injectors for your 7.3L, contact sales@coredieselparts.com.
Frequently asked questions
What is the difference between P0261 and P0262?
P0261 is the cylinder 1 injector circuit reading low and P0262 is the same circuit reading high. Both point at the cylinder 1 injector wiring, connector, or solenoid, from opposite electrical directions.
Is the under-valve-cover connector a common cause?
Yes. On the 7.3L the injector power passes through a connector under the valve cover that oil and heat degrade over time, making it a frequent source of single-cylinder injector codes.
Can I drive with P0262?
You can, but a misfiring cylinder means reduced power, rough running, and extra fuel washing the cylinder. Repair it promptly to avoid further issues.
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