P2303 on 2021-2024 Ford Bronco 2.3L: Ignition Coil 'B' Circuit Causes and Fixes

What's Unique About the 2021-2024 Ford BRONCO

For 2021-2024 Broncos with the 2.3L EcoBoost engine, this code has a significant platform-specific issue documented by Ford. Technical Service Bulletins (TSBs) state that a PCM software glitch can cause incorrect cylinder-to-DTC mapping. This means that while P2303 points to cylinder 2, the actual ignition fault could be on a different cylinder. SSM 52342 further clarifies that due to this mapping error, the PCM may shut off fuel to the cylinder it *thinks* is bad (the one with the DTC), which complicates diagnosis. Technicians are advised to perform a power balance test using a Ford-specific scan tool to identify the true source of the misfire before replacing parts.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• Engine running rough or vibrating, especially at idle
• Noticeable loss of power and hesitation during acceleration.
• Engine may stumble or stall.
• Blinking Check Engine Light during the misfire event, indicating a severe misfire.

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability Coil-on-plug systems are common failure points across many modern engines. Heat and vibration eventually lead to internal coil failure.
   How to confirm: The easiest way to confirm is to swap the ignition coil 🎬 See how to test ignition coils using basic hand tools from the suspected faulty cylinder (identified via power balance test) with another cylinder. Clear the codes and drive. If the misfire code moves to the new cylinder, the coil is confirmed bad.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace the corresponding spark plug at the same time.
   Est. part cost: $40-$85
2. PCM Software Issue (Incorrect Cylinder Mapping) 🟡 Medium Probability This is a documented issue for this specific vehicle and engine combination, as noted in Ford TSBs 24-2406 and SSM 52342. The PCM software incorrectly maps the fault to the wrong cylinder.
   How to confirm: A Ford dealer or a shop with a Ford-specific scan tool (FDRS) can check the current PCM software level against the TSBs. A power balance test will show which cylinder is actually weak, which may not match the DTC.
   Typical fix: Reprogram the Powertrain Control Module (PCM) to the latest software level. This is typically a dealer-only procedure and may be covered under warranty.
   Est. part cost: $0 (if under warranty)
3. Damaged Wiring or Connector ⚪ Low Probability Engine vibrations and heat can cause wiring insulation to become brittle or connectors to loosen over time. The plastic locking tabs on connectors can also become brittle and break.
   How to confirm: Visually inspect the wiring harness and connector going to the suspect ignition coil. Look for any signs of chafing, melting, corrosion on the pins, or a loose connection. Wiggle the connector with the engine running to see if it induces a misfire.
   Typical fix: Repair the damaged section of wiring or replace the ignition coil pigtail connector. The Motorcraft connector kit is part number WPT-1492.
   Est. part cost: $25-$60
4. Worn or Fouled Spark Plug ⚪ Low Probability While a bad spark plug typically sets a misfire code (like P0302), a heavily worn plug with a very large gap can put extra stress on the ignition coil, potentially contributing to a coil circuit fault.
   How to confirm: Remove the spark plug from the cylinder identified in the power balance test and inspect it for wear, carbon fouling, or oil deposits. Check the gap against the manufacturer's specification.
   Typical fix: Replace the spark plug. It's good practice to replace all four at once.
   Est. part cost: $15-$25

Rare But Worth Checking

• Powertrain Control Module (PCM) Failure: This is rare. The internal driver circuit for the ignition coil can fail. Before condemning the PCM, all other possibilities (coil, plug, wiring, and software) must be exhaustively ruled out.

Diagnosis Steps

1. Read the DTCs with an OBD-II scanner. Note that P2303 points to cylinder #2.
2. CRITICAL STEP for this vehicle: Be aware of TSB 24-2406 and SSM 52342. The code may not point to the correct cylinder. A power balance test using a Ford-specific scan tool (FDRS) is required for accurate diagnosis.
3. Perform the power balance test. This test measures the power contribution of each cylinder.
4. Interpret the power balance test results: If only one cylinder shows a drop in performance, that is the faulty cylinder. If TWO cylinders show a drop, TSB SSM 52342 advises to begin diagnosis on the cylinder that is dropping out but is NOT setting an ignition DTC. The PCM is likely disabling fuel to the cylinder it flagged with the code (e.g., Cyl #2 for P2303), causing it to also appear weak. The true fault lies with the other weak cylinder.
5. Once the correct cylinder is identified, visually inspect its ignition coil connector and wiring for any damage or loose connections.
6. To test the coil, swap the ignition coil from the identified faulty cylinder with a coil from a known good cylinder. Clear the codes.
7. Drive the vehicle until the Check Engine Light returns. Scan the codes again. If the code has moved to the new cylinder (e.g., P2300 for Coil 'A'/Cyl #1), the ignition coil is faulty and needs replacement.
8. If the code does not move and remains on the original cylinder, the problem is likely in the wiring or the PCM. Inspect the spark plug in the faulty cylinder for wear or damage.
9. If the plug is good, test the wiring between the PCM and the coil connector for continuity and shorts to ground.
10. If wiring, plug, and coil are all confirmed good, the issue is the PCM software or a faulty PCM driver. Consult a dealer to check for required software updates as per TSB 24-2406.

Parts You'll Likely Need

• Ignition Coil (OEM #DG-576) — This is the most common hardware failure for a P2303 code. This part number supersedes DG-574.
  Trusted brands: Motorcraft
  OEM price range: $80-$90
  Aftermarket price range: $40-$70
• Spark Plug (OEM #SP-594) — It is best practice to replace the spark plug when replacing an ignition coil. A worn plug can cause a new coil to fail prematurely.
  Trusted brands: Motorcraft, NGK
  OEM price range: $15-$25
  Aftermarket price range: $8-$15
• Ignition Coil Pigtail Connector (OEM #WPT-1492) — If the connector or its wiring is damaged from heat or vibration, this pigtail kit is needed to repair the harness.
  Trusted brands: Motorcraft
  OEM price range: $30-$50
  Aftermarket price range: $20-$40

Related Codes That Often Appear With This One

• P0302 — This code means 'Cylinder 2 Misfire Detected'. It is a direct symptom of the ignition failure indicated by P2303.
• P0352 — This code is for 'Ignition Coil 'B' Primary/Secondary Circuit'. It is a related code for the same coil and often appears with P2303, as they both point to a fault in the same component's circuitry.
• P2300, P2306, P2309, etc. — The TSBs for this vehicle list a wide range of ignition coil codes (P035x, P23xx) that can be set due to the PCM software issue. Seeing multiple coil codes at once strongly suggests the software problem.

Technical Service Bulletins (TSBs) & Recalls

• TSB 24-2406: Notes that 2021-2024 Broncos with the 2.3L engine may set various ignition DTCs, including P2303, due to incorrect cylinder-to-DTC mapping in the PCM, and advises a software update.
• SSM 52342: Reinforces the information in TSB 24-2406, stating that a real ignition system concern is present but the code may point to the wrong cylinder. It provides the critical diagnostic instruction to use a power balance test and how to interpret the results if two cylinders appear weak.

Platform-Specific Known Issues

• A PCM software issue can cause incorrect cylinder to DTC mapping. A fault on one cylinder may trigger a code for a different cylinder. TSB 24-2406 recommends a PCM reprogram to correct this.
• SSM 52342 elaborates on this issue, advising technicians to use a power balance test to find the true faulty cylinder before replacing parts. Crucially, it notes the PCM may shut off fuel to the cylinder it *thinks* is bad, causing two cylinders to appear weak on the test. The actual fault is on the weak cylinder that does *not* have a corresponding DTC.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Circuit Resistance — expected: 0.3 - 2.0 Ω (Ohms). Failure: A reading of infinity (Open Loop) or significantly outside the expected range indicates a faulty coil.
• Ignition Coil Secondary Circuit Resistance — expected: 6.5 - 11.5 kΩ (kilo-Ohms). Failure: A reading outside this range suggests an internal failure of the coil's secondary windings.
• Ignition Coil Control Circuit Voltage (using a Noid Light) — expected: A rhythmic flashing light while the engine is cranking or running.. Failure: No light or a steady, non-flashing light indicates a lack of the required ground pulse from the PCM.

Hidden / Shadow Codes Worth Checking

• Mode $06, TID $53: This is not a DTC, but a Test ID within the OBD-II system's Mode $06 data. It provides raw misfire counts for each specific cylinder. This data can reveal intermittent or low-level misfires that have not yet met the threshold to set a P030x trouble code. (see via Requires a scan tool capable of reading Mode $06 data. The data is presented as a test ID (TID) and a component ID (CID), where the CID corresponds to the cylinder number.)

Scan Tool Commands That Help

• Ford FDRS (or equivalent professional scanner): Power Balance Test — This is the most critical diagnostic step for this specific vehicle and code, as mandated by Ford's service bulletins. It graphically displays the power contribution of each cylinder. Use this test *before* replacing any parts to identify the true misfiring cylinder, which may not match the cylinder indicated by the DTC. If two cylinders show a power drop, SSM 52342 states the true fault is on the cylinder that is weak but does *not* have a corresponding ignition DTC.

OEM Part Supersession History

• DG-574 → DG-576 — Standard part revision and improvement by the manufacturer.

Model Year Variations Within This Range

• 2022-2024: While the incorrect cylinder mapping issue applies to all 2021-2024 2.3L Broncos, TSB SSM 52342 specifically calls out 2022-2024 Bronco Raptors built on or before 13-Feb-2024 as being affected, in addition to the standard 2.3L models. This does not change the diagnosis, but notes a specific production range for the Raptor trim.