P0268 — Cylinder 3 Injector Circuit High

Does P0268 always mean the cylinder 3 injector is defective?

No. P0268 identifies an abnormally high voltage condition in the cylinder 3 injector circuit, which can be caused by the injector, an open connection, damaged wiring, a poor ground, or the PCM driver.

Can the vehicle be driven with P0268?

Brief cautious driving may be possible if the engine runs smoothly, but P0268 should be diagnosed promptly. Do not continue driving with severe misfire, major power loss, overheating, or a strong fuel odor.

What test confirms a faulty cylinder 3 injector?

After disconnecting it, compare the cylinder 3 injector resistance with the other injectors and check for an open winding. If resistance is normal, circuit voltage, ground, connector, and PCM-driver tests are still required.

Why does P0268 return after the code is cleared?

Clearing P0268 removes the stored code but does not repair an intermittent open connection, damaged terminal, poor ground, injector failure, or PCM driver problem. The fault must be corrected and then verified under multiple operating conditions.

When your engine control module detects a voltage that stays unusually high on the circuit powering cylinder three's fuel injector, it stores trouble code P0268. The PCM constantly monitors the electrical resistance and voltage at each injector. If the reading on cylinder three's driver circuit climbs above the normal operating range — typically hovering near full battery voltage instead of the pulsed signal the module expects — the system flags this as a malfunction. The result is an illuminated Check Engine light and a logged fault that points directly at that specific cylinder's fuel delivery circuit.

Modern engines rely on precise fuel metering through electrically controlled injectors that spray atomized fuel into the intake port or combustion chamber. Each injector receives a pulsed ground signal from the PCM while battery voltage feeds the other side of the circuit. When everything functions normally, the module rapidly toggles that ground connection to meter fuel based on load, temperature, and throttle position. If something breaks that control — a short to power, an open ground, or a failed injector — the voltage on that signal line rises above specification and P0268 triggers. The ECU stores this code only after confirming the fault across multiple drive cycles, ensuring it's a genuine electrical problem and not a momentary sensor glitch.

Cylinder numbering follows a standard convention: on inline engines, count from the front belt end toward the transmission. V-configuration engines number differently depending on the manufacturer, so consulting your vehicle's firing order diagram is essential before any injector work. This matters because cylinder three sits in different locations depending on engine orientation, and some placements require removing the intake manifold for access — adding significant labor time to the repair bill.

Common Symptoms

• Check Engine light remains illuminated on the dashboard
• Noticeable increase in fuel consumption compared to normal driving patterns
• Rough, uneven idle with occasional engine stumble
• Hesitation or flat spot during acceleration, especially under load
• Reduced engine power when climbing hills or carrying cargo
• Difficulty starting the engine, sometimes requiring extended cranking time

Likely Causes

• Damaged or corroded wiring harness feeding the cylinder three injector circuit
• Failed cylinder three fuel injector with internal short to power
• Open ground return circuit for the cylinder three injector driver
• Signal wire for cylinder three shorted directly to battery positive voltage
• Clogged or dirty fuel injectors restricting proper fuel delivery
• Weak fuel pump unable to maintain adequate rail pressure
• Clogged fuel filter restricting fuel flow to the injectors
• Intake air leaks or vacuum leaks disturbing the air-fuel mixture ratio

How to Diagnose P0268

1. Connect an OBD2 scanner and verify that P0268 is the active or stored code. Record the associated freeze frame data showing engine speed, load, temperature, and vehicle speed at the moment the fault was detected.
2. Scan for any additional diagnostic trouble codes. Related codes such as fuel pressure sensor faults or misfire codes often point toward the root cause of the injector circuit issue. Check for any manufacturer technical service bulletins addressing P0268 for your specific make, model, and model year.
3. Perform a thorough visual inspection of the wiring harness and electrical connector at the cylinder three injector. Look for damaged insulation, broken wires, corrosion buildup, or loose terminal connections that could interrupt the signal.
4. Disconnect the cylinder three injector harness and use a multimeter to measure voltage at the harness side connector. With the injector unplugged, a voltage reading near battery level indicates a short-to-power condition in the wiring. If voltage drops to normal expected levels when the injector is disconnected, the injector itself is the likely culprit.
5. Measure fuel system pressure at the fuel rail Schrader valve with a dedicated fuel pressure gauge. Compare the reading against factory specifications at idle and under simulated load conditions to rule out insufficient fuel delivery.
6. Review live data streams showing short-term and long-term fuel trim values. Positive fuel trims indicate the PCM is adding fuel to compensate for a lean condition, which could point toward injector problems or fuel pressure issues.
7. After clearing the code, complete a drive cycle that reproduces the freeze frame conditions — similar RPM, load, and temperature — and verify that P0268 does not return.

Repair Options

• Replace the fuel pump assembly: $400–$900
• Replace the fuel filter: $80–$200
• Clean or replace fuel injectors: $200–$800
• Replace the fuel pressure regulator or sensor: $150–$450

Total Repair Cost

The final bill hinges entirely on which component is responsible for P0268. Independent shop labor rates typically run $75–$125 per hour, and parts costs vary by brand and vehicle application. Injector replacement or cleaning costs $200–$800, while a full fuel pump replacement including labor ranges $400–$900. A simpler fuel filter swap runs $80–$200, and a pressure regulator or sensor replacement costs $150–$450. Most P0268 repairs fall somewhere between $80 and $900 total. Starting with visual inspection and circuit testing before purchasing parts prevents unnecessary spending — the cheapest fixes are always the first to rule out.

Driving Safety Verdict

Use caution when driving with P0268 stored. An injector circuit malfunction disturbs the air-fuel mixture, which can produce engine stalling, severe hesitation, and rough running that becomes dangerous in heavy traffic. Prolonged operation with a rich fuel mixture may overheat the catalytic converter and cause permanent damage to that emissions component. Avoid extended highway trips or congested driving situations until the underlying fault is identified and corrected.

Related OBD2 Codes

• P0200: Injector Circuit Malfunction
• P0201: Injector Circuit Malfunction - Cylinder 1
• P0202: Injector Circuit Malfunction - Cylinder 2
• P0203: Injector Circuit Malfunction - Cylinder 3
• P0204: Injector Circuit Malfunction - Cylinder 4
• P0205: Injector Circuit Malfunction - Cylinder 5