OBD Code P0202: Injector Circuit/Open – Cylinder 2 – Causes, Symptoms & Fixes

When your vehicle’s onboard diagnostic system triggers code P0202, it’s telling you that there’s an electrical problem with the fuel injector serving cylinder 2 of your engine. This code falls under the fuel system category and means the engine control module (ECM) has detected an open circuit condition—essentially, the electrical signal to the injector is broken or interrupted. This prevents the injector from opening and spraying fuel into cylinder 2, which leads to a misfire and poor engine performance.

What Does P0202 Mean?

P0202 is a standardized OBD-II diagnostic trouble code that specifically addresses the fuel injector circuit for cylinder 2. Here’s the technical breakdown:

• P = Powertrain code (engine, transmission, drivetrain)
• 0 = Generic OBD-II code (applies to all manufacturers)
• 2 = Fuel and air metering system
• 02 = Injector Circuit/Open – Cylinder 2

When the ECM commands the fuel injector to open, it expects to see a specific electrical response. If the circuit is open—meaning there’s a break in the electrical path—the ECM cannot complete the circuit and the injector won’t fire. This is different from a short circuit; an open circuit means the connection is broken, not that it’s touching something it shouldn’t.

The code can be triggered by:

• A faulty fuel injector that won’t respond to electrical signals
• Broken or corroded wiring in the injector harness
• A disconnected or damaged connector at the injector
• Internal ECM driver circuit failure (rare)
• A blown fuse in the fuel injector circuit

Common Symptoms

Drivers typically notice one or more of these symptoms when P0202 is active:

• Check Engine Light (CEL) – Illuminated on the dashboard
• Engine Misfire – Rough, stuttering idle or acceleration; noticeable vibration
• Loss of Power – Reduced acceleration and overall engine performance
• Rough Idle – Engine shakes or runs unevenly at stops
• Fuel Smell – Unburned fuel odor from the exhaust (cylinder 2 isn’t firing)
• Increased Fuel Consumption – Engine compensates by running rich on other cylinders
• Difficulty Starting – Engine may crank but start slowly or hesitantly
• Hesitation During Acceleration – Noticeable lag when pressing the gas pedal

Possible Causes (Ranked by Likelihood)

1. Faulty Fuel Injector (Cylinder 2) – The injector itself has failed electrically and won’t respond to the ECM’s signal. This is the most common cause, especially on higher-mileage vehicles.
2. Broken or Corroded Wiring Harness – The wires connecting the ECM to the injector are damaged, pinched, or corroded, breaking the electrical circuit. Check for visible damage under the valve cover or along the engine bay.
3. Disconnected or Damaged Connector – The electrical connector at the fuel injector has come loose, corroded, or been damaged. This is a quick fix if caught early.
4. Blown Fuel Injector Fuse – A fuse in the fuel injector circuit has blown, cutting power to cylinder 2’s injector. Check your vehicle’s fuse box (usually in the engine bay or under the dash).
5. Poor Ground Connection – The injector or its wiring lacks a proper ground, preventing current flow. Ground issues can be tricky to diagnose but are fixable with proper cleaning and reconnection.
6. ECM Driver Circuit Failure – The engine control module’s internal circuit that controls the fuel injector has failed. This is rare but requires ECM replacement or reprogramming.
7. Fuel Injector Relay Malfunction – The relay controlling power to the fuel injectors has failed, affecting cylinder 2’s injector. Less common but worth checking during diagnosis.

Diagnostic Steps

Follow these steps to diagnose the root cause of P0202:

Step 1: Scan and Document the Code

• Use an OBD-II scanner to confirm code P0202 and check for any related codes (like P0201, P0203, etc., which would indicate multiple injector issues).
• Note the freeze frame data—the engine conditions when the code was triggered.
• Clear the code and test-drive to see if it returns immediately (suggests a hard fault) or intermittently (suggests a connection issue).

Step 2: Visual Inspection

• Locate cylinder 2’s fuel injector (consult your vehicle’s service manual for the exact location).
• Inspect the wiring harness and connector for visible damage, corrosion, or looseness.
• Check for pinched wires or damage from engine heat.
• Ensure the connector is fully seated and not corroded.

Step 3: Check the Fuel Injector Fuse

• Locate the fuel injector fuse in your vehicle’s fuse box (check the owner’s manual or fuse box diagram).
• Remove the fuse and inspect it—a blown fuse will have a broken filament inside.
• If blown, replace with a fuse of the same amperage. If it blows again immediately, there’s a short circuit elsewhere.

Step 4: Test the Injector Connector

• Disconnect the fuel injector connector for cylinder 2.
• With the key in the “On” position (engine off), use a multimeter to check for voltage at the connector terminals.
• You should see approximately 12 volts on the power terminal. If not, trace back to the fuse and relay.

Step 5: Test Injector Resistance

• With the connector disconnected and the key off, use a multimeter set to ohms (resistance) mode.
• Measure the resistance across the injector terminals. Most fuel injectors have a resistance between 10-16 ohms (varies by vehicle).
• If the reading is infinite (∞) or very high, the injector is open internally and needs replacement.
• If the reading is 0 or very low, the injector is shorted and also needs replacement.

Step 6: Check Wiring Harness Continuity

• Set your multimeter to continuity mode.
• Disconnect the injector connector and the ECM connector (or fuel injector driver module).
• Test continuity between the injector terminal and the corresponding ECM terminal.
• If there’s no continuity, the wiring is broken and needs repair or replacement.

Step 7: Test Ground Connection

• Ensure the injector has a solid ground connection. Use a multimeter to check resistance between the injector ground and the engine block.
• Resistance should be very low (less than 1 ohm). High resistance indicates a poor ground that needs cleaning or reattachment.

Step 8: Professional Diagnosis

• If the above steps don’t identify the problem, use a fuel injector tester or oscilloscope to check the injector’s response to ECM commands.
• A professional mechanic can also test the ECM’s driver circuit if all other components check out.

Repair Cost Estimates

The cost to repair P0202 varies widely depending on the root cause and your vehicle:

• Fuel Injector Replacement: $300–$900 per injector (parts + labor). High-performance or direct-injection injectors cost more. Some vehicles have easily accessible injectors (lower labor), while others require valve cover removal (higher labor).
• Wiring Harness Repair/Replacement: $150–$400. If the harness is damaged, it may need partial or full replacement. Labor depends on accessibility.
• Connector Replacement: $50–$150. A simple fix if the connector is the only problem.
• Fuse Replacement: $10–$30. Very cheap, but if the fuse keeps blowing, there’s an underlying short circuit that needs diagnosis.
• Ground Wire Repair: $100–$300. Cleaning and reattaching a ground wire is usually quick; replacement costs more.
• ECM Repair/Replacement: $800–$2,500+. Rare, but if the ECM’s driver circuit is faulty, this is the most expensive fix.

Average Total Cost: For a typical fuel injector replacement on a Ford F-150, Chevrolet Silverado, or Honda Accord, expect $400–$700 in parts and labor combined. Always get a diagnostic quote before authorizing repairs.

Can I Still Drive?

Severity: Moderate to High

Whether you can safely drive with P0202 depends on the severity of the problem:

• Short-term (a few miles): You can likely drive to a mechanic, but expect rough idling and reduced power.
• Extended driving: Not recommended. Continuous misfiring in cylinder 2 can damage the catalytic converter (unburned fuel ignites in the exhaust) and increase emissions significantly.
• Safety concerns: The misfire may cause hesitation during acceleration, making highway merging or passing unsafe. The rough idle can also make the vehicle unpredictable in traffic.
• Emission test: Your vehicle will fail an emissions test with this code active.

Recommendation: Have the code diagnosed and repaired within a few days. If the injector is simply disconnected or a fuse is blown, the fix is quick and inexpensive. If it’s a faulty injector, budget for replacement soon to avoid catalytic converter damage.

Frequently Asked Questions