P0268 — Cylinder 3 Injector Circuit High #

The description of this Diagnostic Trouble Code (DTC) may vary depending on the vehicle manufacturer.

• Cylinder 3 Injector Circuit High (Generic, GM, Ford, Toyota, Honda)
• Injector 3 Control Circuit High (Chrysler)
• Cylinder 3 Fuel Injector Voltage High Input (Nissan)

Summary of DTC P0268 #

P0268 indicates that the Engine Control Module (ECM)—sometimes called the Powertrain Control Module (PCM)—has detected an abnormally high voltage in the fuel injector circuit for cylinder 3. In OBD-II/EOBD systems, each injector is electrically monitored, and a “circuit high” means the measured voltage is above the expected range. This code typically points to an electrical problem, such as a shorted wire, faulty injector, or connector issue, rather than a direct mechanical failure. Depending on the vehicle and driving conditions, P0268 can trigger a Check Engine Light and may be accompanied by noticeable engine performance symptoms. Prompt diagnosis is recommended to avoid potential engine damage over time.

Common Symptoms for DTC P0268 #

When P0268 is stored, the engine may not run as smoothly as usual. The issue can range from subtle to quite pronounced, depending on whether the injector for cylinder 3 is stuck open, unable to function, or if the circuit is simply reporting a false high reading. Here’s what you might notice:

• Check Engine Light (CEL/MIL) illuminated
• Rough idle or engine vibration
• Misfire, especially under load or at idle
• Reduced engine power or hesitation during acceleration
• Possible increase in fuel consumption
• Hard starting or extended crank time

Probable Causes for DTC P0268 #

The most common reasons for a “circuit high” code in cylinder 3’s injector circuit are related to electrical problems. Here are the likely culprits, in order of frequency:

1. Wiring issues—short to voltage or open circuit in the injector wiring harness
2. Faulty injector—internal short or resistance out of specification
3. Poor connector contact—corrosion, bent pins, or loose fit at injector or ECM/PCM connectors
4. ECM/PCM fault—rare, but possible if all other causes are ruled out
5. Aftermarket modifications—incorrect injector replacements or wiring changes

Step-by-Step Diagnostic Process for P0268 #

Carefully diagnosing P0268 requires a logical, stepwise approach to avoid time-consuming guesswork. Here’s how a professional technician typically proceeds:

1. Record the code and freeze frame data with a scan tool to note when and how the code set.
2. Visually inspect the cylinder 3 injector, its connector, and the relevant wiring harness for damage, corrosion, or loose connections.
3. Check injector resistance at the connector using a multimeter. Compare readings to OEM specifications.
4. Test for voltage at the injector connector with the key on, engine off (KOEO).
5. Backprobe ECM/PCM pins for continuity and shorts to power or ground.
6. Swap injectors (if accessible) between cylinders to see if the code follows the injector or stays with the circuit.
7. Check ECM/PCM outputs if all wiring and injector tests pass.

Possible Repairs for DTC P0268 #

The correct repair depends on the root cause identified during diagnostics. Here’s what typically resolves P0268—always verify repair effectiveness by clearing codes and retesting:

• Repair or replace damaged wiring or connectors in the cylinder 3 injector circuit
• Replace the cylinder 3 fuel injector if resistance is out of spec or faulty
• Clean and secure all connections at the injector and ECM/PCM
• Replace ECM/PCM (only if confirmed as faulty—rare)
• Correct any improper aftermarket wiring or injector installation

Is It Safe to Drive with Code P0268? #

Limited: While you may be able to drive short distances with P0268 present, it’s not recommended for prolonged use. An injector circuit high condition can cause misfires and poor engine performance, potentially leading to catalytic converter damage, increased emissions, or even engine damage over time. If the engine is running noticeably rough or misfiring, reduce driving and seek repair as soon as possible.

Vehicles Most Commonly Affected by P0268 #

P0268 is a generic OBD-II code and can appear on any modern gasoline or diesel vehicle with sequential fuel injection. However, it is most frequently reported on:

• Chevrolet and GMC trucks (Silverado, Sierra, Colorado)
• Ford F-series (F-150, F-250), and Focus/Escape
• Honda Accord and Civic
• Toyota Corolla, Camry, Tacoma
• Nissan Altima, Sentra
• Chrysler/Dodge RAM pickups

Common Mistakes & Best Practices for P0268 #

Misdiagnosis is common with injector circuit codes. To avoid wasted time and parts, keep these tips in mind:

• Don’t replace the injector first—always check wiring and connectors before replacing parts
• Verify the code is current—clear the code and see if it returns after basic checks
• Do not ignore TSBs (Technical Service Bulletins)—OEMs often release bulletins for known wiring or ECM issues
• Use the correct injector for your engine—mixing parts can trigger false codes
• Document all findings for future reference or warranty claims

Express FAQ for Code P0268 #

Got questions? Here are a couple of quick answers:

• Q: Can a simple loose connector trigger P0268?
  A: Absolutely—corrosion, looseness, or a poor fit at the injector or PCM connector can cause abnormal voltage readings and set this code.
• Q: Does P0268 always mean the injector is bad?
  A: Not necessarily. While a failed injector is possible, wiring or connector issues are just as likely. Test before replacing any parts.