OBD Code P0205: Cylinder 5 Injector Circuit Open or Short

When your vehicle’s onboard diagnostic system triggers code P0205, it means the engine control module (ECM) has detected an electrical problem with the fuel injector that supplies fuel to cylinder 5. This is a moderate-severity code that affects fuel delivery and engine performance. Unlike some codes that may be safely ignored temporarily, P0205 should be addressed promptly to prevent engine damage and poor fuel economy.

What Does P0205 Mean?

P0205 is a standardized OBD-II diagnostic trouble code that specifically targets cylinder 5’s fuel injector circuit. The code breaks down as follows:

• P = Powertrain code
• 0 = Generic (manufacturer-independent)
• 2 = Fuel and air metering system
• 05 = Cylinder 5 injector circuit

The ECM monitors fuel injector circuits for proper voltage and resistance. When it detects an open circuit (broken wire, disconnected connector, or failed injector) or a short circuit (wire touching ground, internal injector failure, or shorted wiring), it logs code P0205 and illuminates the check engine light.

Note: Cylinder numbering varies by vehicle. In V6 engines, cylinder 5 is typically the middle cylinder on one bank. In V8 engines, it’s usually the second cylinder on one side. Always consult your vehicle’s service manual to identify the correct cylinder location.

Common Symptoms

• Check Engine Light (CEL) – The primary indicator that P0205 has been detected
• Rough Idle – Engine may shake or vibrate at stoplights and idle speeds
• Misfires – Cylinder 5 may not fire, causing hesitation and jerking during acceleration
• Poor Fuel Economy – Engine compensates by running rich or adjusting timing
• Loss of Power – Reduced acceleration and overall engine performance
• Black Smoke from Exhaust – Unburned fuel exits the tailpipe (if injector is stuck open)
• Fuel Smell – Raw fuel odor inside or around the vehicle
• Hard Starting – Engine cranks but takes longer to start
• Cylinder 5 Misfire Code – Often accompanied by P0305 (Cylinder 5 Misfire Detected)

Possible Causes (Ranked by Frequency)

1. Faulty Fuel Injector (Most Common)

The fuel injector itself has failed internally, causing an open or short circuit. This is the most common reason for P0205. Injectors can fail due to carbon buildup, electrical coil failure, or mechanical wear over time. Typical lifespan is 50,000-100,000 miles depending on fuel quality and maintenance.

2. Corroded or Loose Injector Connector

The electrical connector that plugs into the injector has corroded, loosened, or become disconnected. Water intrusion, heat cycling, and vibration can degrade connectors over time. This is often the easiest and least expensive fix.

3. Damaged Injector Wiring

The wiring harness leading to cylinder 5’s injector is damaged, pinched, or shorted. This can occur from engine vibration, rodent damage, or improper reassembly after maintenance. A short to ground will cause the ECM to detect a circuit fault.

4. Failed Fuel Injector Driver (ECM/PCM Issue)

The ECM’s internal circuit that controls the fuel injector has failed. This is relatively rare but possible in older vehicles or those with electrical damage. Requires ECM replacement or reprogramming.

5. Blown Fuel Injector Fuse or Relay

The dedicated fuse or relay controlling cylinder 5’s injector circuit has blown. Check the fuse box for a burned-out fuse. A blown fuse indicates an underlying short circuit that must be addressed.

6. Broken Injector Mounting or Ground

The fuel injector’s mounting bracket is cracked, or the ground wire connection is loose or corroded. Poor grounding prevents proper circuit completion.

Diagnostic Steps

Step 1: Scan for Related Codes

Use an OBD-II scanner to retrieve all stored and pending codes. P0205 often appears alongside P0305 (Cylinder 5 Misfire). Note any other fuel system codes (P0200-P0209) which may indicate a broader issue.

Step 2: Visual Inspection

Locate cylinder 5 on your engine (refer to the service manual for your specific vehicle). Visually inspect:

• The fuel injector connector – look for corrosion, loose pins, or water intrusion
• The wiring harness – check for cuts, pinches, melting, or rodent damage
• The fuel injector itself – look for cracks, leaks, or obvious damage
• The fuel rail and mounting – ensure the injector is properly seated

Step 3: Check Connector and Wiring

Disconnect the fuel injector connector and inspect the pins for corrosion or damage. Clean with electrical contact cleaner if needed. Reconnect firmly and listen for a click. Use a multimeter to test for continuity along the wiring harness from the injector to the ECM. A break in continuity indicates a wiring problem.

Step 4: Test Injector Resistance

With the ignition off and the connector disconnected, use a multimeter set to ohms (Ω) to measure the fuel injector’s internal resistance. Most fuel injectors read between 12-16 ohms (high-impedance) or 2-4 ohms (low-impedance). Check your vehicle’s service manual for the correct specification. A reading of 0 ohms or infinity indicates a failed injector.

Step 5: Test for Voltage and Ground

With the ignition on (engine off), use a multimeter to check for 12V at the injector connector. Crank the engine and observe voltage pulsing – the ECM should pulse the injector on and off. No voltage indicates a wiring or ECM issue. No pulsing indicates an ECM driver problem.

Step 6: Fuel Pressure Test

Connect a fuel pressure gauge to the fuel rail. Key on, engine off, pressure should hold steady (typically 35-65 PSI depending on vehicle). If pressure drops when the engine is running, a leaking injector (stuck open) may be the cause.

Step 7: Check Fuses and Relays

Locate the fuel injector fuse and relay in the fuse box (consult your owner’s manual). Inspect the fuse for a broken filament. Test the relay by swapping it with an identical relay from another circuit to see if the problem moves. A blown fuse indicates a short circuit that must be traced.

Step 8: Clear Code and Test Drive

After performing repairs, clear the code using your scanner and take a test drive. Monitor for code return. If the code doesn’t return after 50+ miles of driving, the repair was successful.

Repair Cost Estimates

Cost Factors: Luxury and European vehicles typically cost 20-40% more than domestic vehicles. Some injectors require fuel rail removal, increasing labor time. OEM parts are more expensive than aftermarket alternatives but often more reliable.

Can I Still Drive?

Severity: Moderate

You can typically drive short distances with code P0205, but it’s not recommended for extended highway driving. Here’s what to expect:

• Drivability: The vehicle will run rough and may hesitate during acceleration. Fuel economy will suffer noticeably.
• Safety: The main risk is engine misfiring causing loss of power during merging or passing. This could be dangerous in heavy traffic.
• Engine Damage: A stuck-open injector can wash down cylinder walls with excess fuel, thinning engine oil and potentially causing internal damage over time.
• Emissions: The vehicle will likely fail an emissions test and may not be street-legal depending on local regulations.

Recommendation: Have the code diagnosed and repaired within a few days. If you must drive, avoid highway speeds and heavy acceleration. Monitor engine temperature and oil level closely.

Frequently Asked Questions

Can a bad fuel injector cause P0205?

Yes, absolutely. A faulty fuel injector is the most common cause of P0205. Internal coil failure, carbon buildup, or mechanical wear can cause the injector to develop an open or short circuit. The ECM detects this electrical fault and triggers the code. Fuel injectors typically last 50,000-100,000 miles before failure becomes likely.

What’s the difference between an open and short circuit in a fuel injector?

An open circuit means the electrical path is broken – the injector won’t receive power and won’t fire. A short circuit means the electrical path is compromised, often with current flowing to ground instead of through the injector coil. Both prevent proper fuel injection. An open circuit typically results in a lean condition and misfire, while a short may cause the ECM to shut down the injector to protect the circuit.

Will replacing the fuel injector fix P0205?

In most cases, yes. If the injector itself is faulty (which accounts for roughly 60-70% of P0205 cases), replacement will resolve the code. However, if the problem is a corroded connector, damaged wiring, or blown fuse, you must address those issues first. Always perform a complete diagnostic before replacing the injector to avoid unnecessary expense.

Can I drive with a bad fuel injector?

You can drive short distances, but it’s not ideal. A faulty injector causes rough idle, misfires, and poor fuel economy. If the injector is stuck open, raw fuel enters the cylinder and can dilute engine oil, potentially causing long-term engine damage. If it’s stuck closed, that cylinder won’t fire at all. For safety and to prevent engine damage, have it repaired as soon as possible.

How much does it cost to fix P0205?

Repair costs range from $110 to $700+ depending on the underlying cause. A simple connector cleaning or fuse replacement might cost $100-$300, while fuel injector replacement typically runs $225-$700. Luxury vehicles and those requiring fuel rail removal cost more. Always get a diagnostic first – you may not need an expensive injector replacement if the issue is just a loose connector.