P0202 DTC: Injector Circuit/Open - Cylinder 2 Explained

Quick answer

• What it means: The Powertrain Control Module (PCM) has detected an open circuit or electrical issue in the fuel injector circuit for cylinder 2.
• Severity: Moderately severe; prolonged driving can lead to engine damage or reduced fuel economy.
• Most common cause: A faulty fuel injector or wiring issue to the injector.

What the P0202 code means

The official OBD-II definition for P0202 is "Injector Circuit/Open - Cylinder 2." In plain English, this means that your vehicle's computer (the PCM) has identified a problem with the electrical circuit that controls the fuel injector for cylinder number 2. An "open" circuit means that electricity is not flowing as it should through that part of the system, preventing the injector from firing properly. This directly impacts the engine's ability to deliver fuel to that specific cylinder, leading to a misfire and a noticeable change in engine performance.

Fuel injectors are electronically controlled valves that spray a fine mist of fuel into the engine's combustion chambers. The PCM controls when and how long these injectors open, which directly affects the air-fuel mixture. When the circuit for Cylinder 2's injector is open, the PCM cannot command it to open, which means no fuel (or insufficient fuel) is delivered to that cylinder. The PCM monitors the voltage and resistance within the injector circuits, and when it detects a reading outside of the manufacturer's specified range for Cylinder 2, it sets the P0202 code and illuminates the Check Engine Light.

Common symptoms

When a P0202 code is present, you might experience one or more of the following symptoms:

• Check Engine Light illuminated: This is almost always the first sign.
• Engine misfire: The engine will likely run rough, stumble, or shake, especially at idle.
• Reduced engine performance: You might notice a significant loss of power and slower acceleration.
• Poor fuel economy: If the engine is trying to compensate for the lack of fuel in one cylinder, it can waste fuel.
• Rough idle or stalling: The engine may struggle to maintain a consistent idle speed or even shut off.
• Engine knocking or pinging: In some cases, detonation can occur if the air-fuel mixture is severely off.
• Raw fuel smell from the exhaust: Unburnt fuel may exit the exhaust if other cylinders are running rich to compensate.

Common causes

Here are the most common causes for a P0202 code, ranked from most to least likely:

1. Faulty fuel injector (Cylinder 2): The injector itself may have an internal electrical fault, preventing it from opening or closing properly. This is the most common cause.
2. Wiring issue to the injector (Cylinder 2): Damaged, chafed, or corroded wiring in the injector's power or ground circuit can create an open circuit. This could include a broken wire, a loose connection at the injector, or corrosion in the connector.
3. Faulty PCM (Powertrain Control Module): While less common, a defective PCM could fail to send the correct signal to the injector or properly monitor its circuit. This is usually considered after all other possibilities have been ruled out.
4. Bad connection at the PCM: Corrosion or a loose pin within the PCM connector for the cylinder 2 injector circuit could cause the issue.

How a technician diagnoses it

Diagnosing a P0202 code requires a systematic approach, often involving a multimeter and a scan tool with advanced capabilities.

1. Verify the code and check for other codes: The technician will connect an OBD-II scan tool to confirm the P0202 code and check for any other related or contributing codes (e.g., misfire codes like P0302).
2. Inspect the wiring and connector: Visually inspect the wiring harness leading to the Cylinder 2 fuel injector for any signs of damage, fraying, corrosion, or loose connections. Wiggle the connector to see if it affects the engine's operation.
3. Perform a "Noid light" test: A noid light is a specialized test light that plugs directly into the fuel injector connector. While the engine is cranking or running, a flashing noid light indicates that the PCM is sending a pulse to the injector. If it doesn't flash, the problem is upstream (wiring or PCM). If it flashes, the problem is likely the injector itself.
4. Measure resistance of the injector: With the ignition off and the injector connector unplugged, the technician will use a digital multimeter to measure the resistance across the two terminals of the Cylinder 2 fuel injector. A typical resistance range for most injectors is between 10-18 ohms. A reading significantly outside this range (e.g., infinite resistance or 0 ohms) indicates a faulty injector.
5. Check for power and ground at the injector connector: With the injector unplugged, the technician will use a multimeter to check for power at one terminal of the connector (usually 12V battery voltage with the key on or engine running) and a pulsing ground at the other terminal while the engine is cranking or running (using a test light or oscilloscope).
6. Swap injector (diagnostic purposes): If the initial tests point to a faulty injector, a technician might swap the Cylinder 2 injector with an injector from another cylinder (Cylinder 1 or 3, for example) to see if the P0202 code moves to the new cylinder. If the code follows the injector, the injector is confirmed bad. If the code stays on Cylinder 2, the issue is with the wiring or PCM.
7. Check PCM drivers (advanced): In rare cases where wiring and the injector are confirmed good, the technician might need to test the PCM's driver circuit for the Cylinder 2 injector using an oscilloscope to verify if the PCM is correctly sending the ground signal.

Typical repair cost

The cost to repair a P0202 code can vary depending on the root cause and your vehicle's make and model. Here are some estimated ranges:

• Fuel Injector Replacement:
  • Parts: $80 - $300 per injector (can vary greatly by vehicle).
  • Labor: $150 - $400 (generally 1-3 hours of labor).
  • Total: $230 - $700
• Wiring Repair:
  • Parts: Minimal (connectors, wire, electrical tape) - $10 - $50.
  • Labor: $100 - $350 (depends on complexity of the repair).
  • Total: $110 - $400
• PCM Replacement/Reprogramming: (Less common)
  • Parts: $500 - $1,500 (depending on vehicle and whether it's new or remanufactured).
  • Labor: $150 - $500 (includes programming).
  • Total: $650 - $2,000

These costs do not include diagnostic fees, which typically range from $100 to $200 and may be applied towards the repair.

Can I keep driving with this code?

It is generally not recommended to keep driving with a P0202 code for an extended period. While you might be able to drive the vehicle a short distance to a repair shop, ignoring this code can lead to more severe problems:

• Engine damage: A continuously un-fueled cylinder can cause unburnt fuel to wash away oil from the cylinder walls, leading to increased wear and potential damage to the cylinder, piston rings, and catalytic converter.
• Catalytic converter damage: Raw fuel entering the exhaust system due to a misfire can overheat and destroy the catalytic converter, a very expensive repair.
• Reduced fuel economy: The engine will run inefficiently, wasting fuel.
• Safety hazard: Reduced engine power and erratic performance can be dangerous, especially in traffic or on highways.

Get the vehicle diagnosed and repaired as soon as possible after the Check Engine Light illuminates with a P0202 code.

Related codes

• P0201: Injector Circuit/Open - Cylinder 1
• P0203: Injector Circuit/Open - Cylinder 3
• P0302: Cylinder 2 Misfire Detected
• P0171: System Too Lean (Bank 1)
• P0174: System Too Lean (Bank 2)

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