P0205 – Injector Circuit/Open Cylinder 5

P0205 is a diagnostic trouble code that points to a problem with the fuel injector circuit on cylinder 5. When this code sets, your engine computer (ECU/PCM) has detected an electrical issue that can cause rough running, misfires, and poor fuel economy. Sometimes it’s just a loose connector or damaged wiring, other times the injector itself has failed. In this guide, you’ll learn what P0205 means, common symptoms, how a mechanic diagnoses it, typical repair options, and whether it’s safe to keep driving with this code stored.

What Does P0205 Mean?

P0205 stands for “Injector Circuit Malfunction – Cylinder 5.” Your ECU constantly monitors the voltage and current going to each fuel injector. If it sees an open circuit, short to power, short to ground, or an electrical value outside the expected range on injector #5, it stores P0205 and usually turns on the check engine light.

This code is about the electrical circuit, not just fuel delivery. That means the fault can be in the injector itself, the wiring harness, the connector, or even inside the ECU. Mechanical issues like low compression in cylinder 5 can trigger related misfire codes, but P0205 is specifically pointing you to the injector circuit for that cylinder.

Quick Reference

• Code: P0205 – Injector Circuit Malfunction, Cylinder 5
• Severity: Moderate to serious (can cause misfire and drivability issues)
• Most common cause: Faulty injector or damaged wiring/connector at cylinder 5
• Typical symptoms: Rough idle, misfire, poor MPG, check engine light
• Risk: Possible catalyst damage and engine wear if ignored

Real-World Example / Field Notes

In the shop, I see P0205 most often on higher-mileage trucks and V6/V8 sedans where cylinder 5 is buried under an intake or near the firewall. One example: a V8 pickup came in with a flashing check engine light, rough idle, and raw fuel smell. Scan tool showed P0205 and a misfire on cylinder 5. The owner had already installed new spark plugs and coils with no change. A quick voltage check at the injector connector showed no power on one pin. Tracing the harness revealed a chafed wire where it rubbed on a bracket. Repairing and insulating the wire cleared the code and restored smooth operation.

Symptoms of P0205

• Check engine light on: P0205 usually sets a steady CEL, sometimes flashing if misfire is severe.
• Rough idle: Cylinder 5 may not be contributing properly, causing shaking at idle.
• Engine misfire: Noticeable hesitation, stumbling, or lack of power under load.
• Poor fuel economy: Unburned fuel or uneven combustion can drop MPG.
• Fuel smell from exhaust: A dead injector or intermittent firing can cause a rich exhaust odor.
• Hard starting: In some cases, extended crank or rough start when the engine is cold.
• Loss of power: The engine may feel weak, especially when accelerating or towing.

Common Causes of P0205

Most Common Causes

• Faulty fuel injector (cylinder 5): Internal coil failure, shorted windings, or open circuit inside the injector body.
• Damaged injector wiring: Broken, chafed, or corroded wires between the injector and ECU, especially near hot engine components.
• Poor injector connector contact: Loose pins, bent terminals, or corrosion at the cylinder 5 injector plug.
• Short to ground or power: Harness rubbing on metal parts or exhaust components can create shorts that trigger P0205.

Less Common Causes

• ECU/PCM driver failure: The internal injector driver circuit for cylinder 5 can fail, especially on older or water-damaged modules.
• Aftermarket modifications: Poor-quality remote start, alarm, or performance wiring spliced into injector circuits.
• Rodent damage: Chewed injector harness, common on vehicles that sit outside or unused for long periods.
• Connector contamination: Oil, coolant, or water intrusion into the injector or ECU connectors affecting the signal.
• Previous repair damage: Pinched or improperly routed harness after engine, intake, or head work.

Diagnosis: Step-by-Step Guide

To properly diagnose P0205, you’ll want at least a basic scan tool, a digital multimeter, and ideally a wiring diagram for your specific vehicle. A noid light or an oscilloscope helps confirm injector pulse, but you can get far with basic tools if you’re careful and methodical.

1. Confirm the code and check for companions. Scan the vehicle and note any related codes like misfires (P0305) or other injector circuit codes. Clear codes and see if P0205 returns immediately or only under certain conditions.
2. Perform a visual inspection. With the engine off, inspect the cylinder 5 injector and harness. Look for broken insulation, burnt spots, loose connectors, or anything rubbing on the valve cover or exhaust.
3. Identify cylinder 5. Use a service manual or under-hood diagram. On V engines, cylinder numbering varies by manufacturer, so don’t guess.
4. Check injector connector fit. Unplug the injector, inspect the terminals for corrosion or spread pins, then reconnect firmly. Sometimes just a poor connection is enough to set P0205.
5. Test injector resistance. With the connector unplugged and key off, measure resistance across the injector terminals using a multimeter. Compare to spec (often 11–18 ohms for many port injectors, but check your manual). An open circuit or very low resistance indicates a bad injector.
6. Verify power supply. Turn key ON (engine off). With a multimeter or test light, check for battery voltage on the injector power wire (usually shared with other injectors). If others have power but #5 does not, you likely have a wiring issue on that branch.
7. Check injector control signal. Use a noid light or oscilloscope on the control wire while cranking or idling. You should see a pulsing signal. No pulse on #5 but good pulse on other cylinders can point to a wiring open or ECU driver fault.
8. Wiggle test the harness. With the engine running (if possible) and a scan tool watching misfire data or injector status, gently move the harness near cylinder 5. If the engine stumbles or the code sets during movement, you’ve likely got an intermittent wiring issue.
9. Swap components if accessible. On some engines, you can swap injector #5 with another cylinder. If the fault follows the injector (P0205 becomes P020X for the new cylinder), the injector is bad. If it stays on cylinder 5, focus on wiring or ECU.
10. Check Mode $06 data (advanced). Some scan tools allow you to see individual cylinder misfire and injector performance data. This can help confirm that cylinder 5 is the only one affected and how often the fault occurs.

Pro tip: Don’t condemn the ECU until you’ve verified power, ground, and continuity on both injector wires from the connector all the way to the ECU plug. ECU failures are much rarer than wiring or injector problems.

Possible Fixes & Repair Costs

Repairs for P0205 depend on what you find during diagnosis. In many cases, the fix is straightforward: replace the cylinder 5 injector or repair a damaged section of wiring. Other times, especially with ECU driver failures, costs can climb quickly. Labor time varies a lot depending on how hard it is to access cylinder 5 on your engine layout.

• Replace cylinder 5 injector: Parts $75–$300 per injector, labor 0.7–2.5 hours. Total typically $200–$600.
• Repair or replace injector wiring/connector: Simple splice or connector replacement $100–$250; larger harness repairs $200–$600 depending on access.
• ECU/PCM replacement and programming: $500–$1,500+ including coding and setup, usually a last-resort fix after all other causes are ruled out.
• Related maintenance (optional): If injectors are old, some owners choose to replace the full bank or set, which can add $300–$800 in parts.

Typical repair cost ranges for P0205 at a professional shop run from about $200 on the low end (simple wiring repair) up to $1,000+ if access is difficult or an ECU is needed. Factors that affect cost include vehicle make, engine layout, injector type (direct vs port injection), parts availability, and local labor rates.

Can I Still Drive With P0205?

You can often drive for a short distance with P0205, but it’s not recommended as a long-term plan. If cylinder 5 isn’t fueling correctly, you’re likely running with a misfire or very uneven combustion. That can overheat the catalytic converter, wash down cylinder walls with fuel, and leave you stranded if the injector circuit fails completely. If the check engine light is flashing, treat it as urgent: reduce load, avoid highway speeds, and get the vehicle inspected as soon as possible.

What Happens If You Ignore P0205?

Ignoring P0205 can lead to more expensive repairs. A persistent misfire from a dead or intermittent injector can damage the catalytic converter, foul spark plugs, cause carbon buildup, and increase internal engine wear. Fuel dilution of the engine oil is also possible if raw fuel enters the cylinder without burning, which reduces lubrication and can shorten engine life.

Last updated: February 13, 2026

Vehicles Commonly Affected by P0205

P0205 can show up on almost any modern fuel-injected engine, but it’s especially common on V6 and V8 engines where cylinder 5 is harder to reach and the injector harness runs near hot components. You’ll often see this code on:

• Ford F-150, Expedition, Explorer, and Mustang V6/V8 engines
• Chevrolet/GMC Silverado, Sierra, Tahoe, Suburban, and Camaro
• Dodge/Ram Ram 1500/2500, Charger, Challenger, and Durango
• Toyota Tacoma, Tundra, 4Runner, and some V6 Camry/Avalon models
• Nissan Frontier, Titan, Pathfinder, and VQ-series V6 cars
• European V6/V8 BMW, Mercedes-Benz, and Audi models with aging injector harnesses

Age, heat, and vibration are the big enemies here, so trucks, SUVs, and performance cars that see heavy use tend to be more prone to injector circuit issues like P0205.