P0352 on 2013-2018 Ford C-Max: Ignition Coil 'B' Circuit Fixes

What's Unique About the 2013-2018 Ford C-Max

The 2.0L Atkinson-Cycle Hybrid engine in the C-Max uses a standard coil-on-plug ignition system that is shared with other Ford models like the Fusion and Escape. There are no unique, hybrid-specific complexities related to this particular code. The diagnostic process is straightforward and typical for most modern four-cylinder engines. The North American Ford C-Max was a single generation (2013-2018), so these fixes apply uniformly across the entire year range.

Symptoms You May Notice

• Check Engine Light is on (may be flashing if the misfire is severe)
• Rough or vibrating idle
• Engine hesitation or stumbling during acceleration
• Reduced engine power and poor fuel economy
• Difficulty starting the engine

Most Likely Causes

1. Failed Ignition Coil on Cylinder #2 🔴 High Probability → Shop Ignition Coil Ignition coils are wear-and-tear items that fail over time due to heat and vibration. It's the most common failure point for any P035x code.
   How to confirm: Swap the ignition coil from cylinder #2 with another cylinder (e.g., cylinder #1). Clear the codes and run the engine. If the code changes to P0351 (for cylinder #1), the coil is definitively bad.
   Typical fix: Replace the faulty ignition coil. It is recommended to use a quality OEM brand like Motorcraft to avoid premature failure of cheaper aftermarket parts.
   Est. part cost: $40-$75
2. Worn or Fouled Spark Plug in Cylinder #2 🟡 Medium Probability → Shop Spark Plug A worn spark plug can increase the electrical resistance, forcing the ignition coil to work harder and potentially causing it to fail. It can also be the source of the misfire itself.
   How to confirm: After ruling out the coil, remove the spark plug from cylinder #2. Inspect it for a worn electrode, cracks in the porcelain, or heavy carbon/oil deposits.
   Typical fix: Replace the spark plug. It is good practice to replace all four spark plugs at the same time if they are near the end of their service life (up to 100,000 miles).
   Est. part cost: $10-$20 per plug
3. Damaged Wiring or Connector ⚪ Low Probability Vibrations and heat can cause wires to chafe or the plastic connector to become brittle and crack over time. In some Ford platforms, extreme heat has led to severe damage; for instance, NHTSA ODI #11270907 notes an instance where a wiring harness actually melted on an ignition coil, causing the vehicle to lose power or stutter.
   How to confirm: Visually inspect the wiring harness and the plastic connector going to the cylinder #2 ignition coil. Look for signs of melting, corrosion, chafed wires, or loose pins in the connector. A loose ECU connector has also been documented as a rare cause.
   Typical fix: Repair the damaged section of wire or replace the connector pigtail. The Motorcraft pigtail is part number WPT-1287 (Ford part CU2Z-14S411-YA).
   Est. part cost: $15-$30 for a pigtail

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare and should only be considered after all other possibilities (coil, plug, wiring) have been exhaustively ruled out. A failed coil driver inside the PCM can mimic a bad coil. This typically requires professional diagnosis to confirm. NHTSA ODI #10644521 describes a case where an owner replaced all spark plugs and the specific coil, but the P0352 code persisted, pointing toward a potential PCM fault.
• Rodent Damage to Wiring: Soy-based wiring insulation used in many modern cars can attract rodents, who may chew through the ignition coil wiring harness, causing an open or short circuit. Look for signs of chewing or nesting material in the engine bay.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner to confirm P0352 is present.
2. Locate cylinder #2. On the 2.0L I4 engine, the cylinders are numbered 1-2-3-4 from left to right as you face the engine from the front of the car.
3. Swap the ignition coil from cylinder #2 with the coil from cylinder #1.
4. Clear the diagnostic trouble codes using the scanner.
5. Start the engine and let it run for a minute or two. Re-scan for codes.
6. If the code has changed to P0351 ('Ignition Coil 'A' Circuit Malfunction'), the ignition coil you moved is faulty and must be replaced.
7. If the code P0352 returns, the problem is not the coil. The next step is to inspect the spark plug in cylinder #2.
8. If the spark plug and coil are both good, carefully inspect the wiring and connector for cylinder #2 for any visible damage, looseness, or corrosion.
9. Using a multimeter, you can check for 12V power and a good ground at the coil connector with the key on, engine off. Check a wiring diagram for the specific pinout.
10. If no external wiring issues are found, the fault may be with the PCM, which requires advanced diagnostics.

Parts You'll Likely Need

• Ignition Coil (OEM #DG-541 (Motorcraft part number 4M5Z-12029-BC)) — This is the most common cause of a P0352 code. The coil is responsible for generating the high voltage for the spark plug. 🎬 Watch: Step-by-step walkthrough for replacing a faulty ignition coil
  Trusted brands: Motorcraft, NGK, Bosch
  OEM price range: $60-$75
  Aftermarket price range: $35-$55
• Iridium Spark Plug (OEM #SP-530 (Motorcraft part number AYFS-32Y-R)) — A worn or fouled spark plug can cause a misfire and may be the underlying cause of the code, or it may be replaced as good practice while servicing the coil.
  Trusted brands: Motorcraft, NGK
  OEM price range: $12-$18
  Aftermarket price range: $8-$15
• Ignition Coil Connector Pigtail (OEM #WPT-1287 (Ford part CU2Z-14S411-YA)) — If the plastic locking tab on the connector is broken or the terminals are corroded, replacing the pigtail is necessary for a secure connection.
  Trusted brands: Motorcraft, Dorman
  OEM price range: $25-$35
  Aftermarket price range: $15-$25

Related Codes That Often Appear With This One

• P0302 — P0302 means 'Cylinder 2 Misfire Detected'. Since P0352 indicates a fault in the ignition system for cylinder 2, it is the direct cause of the misfire, so these codes almost always appear together. 🎬 See this guide on diagnosing Cylinder 2 misfire causes NHTSA ODI #11681823 documents a vehicle exhibiting multiple misfire codes (P0300, P0304, P0305, P0306) alongside P0352.

Technical Service Bulletins (TSBs) & Recalls

• TSB 17-0039: Addresses a thumping/rubbing or grinding noise from the HF35 transmission on vehicles built on or before 15-Aug-2015.
• TSB 25-2081: Provides a software update procedure for various modules to address a 12V battery drain condition.
• SSM 46368: Pertains to 2016 C-Max Energi/Focus Electric and 2016-2017 Fusion Energi vehicles that may exhibit a 12-volt battery drain.
• Bulletin #SSM 52455: Notes that various Ford vehicles equipped with gas engines may exhibit an illuminated MIL with ignition system DTCs including P0352 and P0353 set in the powertrain control module.
• Bulletin #TSB 24-2406: Indicates that certain Ford EcoBoost engines may exhibit an illuminated MIL with ignition system DTCs P0352, P0353, P0354, and P0355 set in the PCM.

Platform-Specific Known Issues

• Some owners on forums like cmaxchat.com anecdotally report that coils on cylinders #2 and #3 may fail more frequently, possibly due to higher heat exposure in the middle of the engine block, but this is not confirmed by official documentation.

Mechanic-Grade Diagnostic Values

• Ignition Coil Connector - Power Supply Voltage — expected: 12V+ (Battery Voltage). Failure: Significantly less than 12V or 0V indicates a wiring or fuse issue.
• Ignition Coil Primary Winding Resistance — expected: Typically very low, between 0.4 and 2.0 ohms.. Failure: A reading of infinity (OL) indicates an open circuit, while a reading of 0 ohms indicates a short. Any reading far outside the typical range suggests a faulty coil.
• Ignition Coil Secondary Winding Resistance — expected: Typically between 6,000 and 15,000 ohms (6k-15k Ω).. Failure: A reading outside the manufacturer's specified range indicates a faulty coil.

Scan Tool Commands That Help

• FORScan / Ford IDS: Power Balance Test — This test graphically displays the contribution of each cylinder, allowing a technician to visually confirm that cylinder #2 is underperforming, which helps verify the misfire location before swapping parts.
• FORScan / Ford IDS: Mode $06, Test ID $53 — To view raw misfire counts per cylinder for the current and last 10 driving cycles. This can confirm if cylinder #2 is the only one misfiring, even if a P0302 code is not yet present.

Wiring & Ground Locations

• Powertrain Control Module (PCM) — Located in the front of the left front wheelwell.. The PCM contains the coil driver circuit that controls the firing of ignition coil #2. A loose connector or internal PCM fault can be a rare cause of P0352.
• G108 — A primary engine ground point located on the top of the transmission.. A poor ground connection at this point can cause various electrical issues within the powertrain system, including erratic behavior of ignition components.
• G105 — A ground point located on the left side of the engine compartment.. This is another critical ground for engine electronics. Verifying it is clean and tight is a good step when diagnosing any electrical fault code like P0352.
• Battery Junction Box (BJB) — Located on the left side of the engine compartment, near the battery.. This box contains the fuses and relays that supply power to the PCM and the ignition coils. A blown fuse or corroded connection here could cut power to the coil circuit.

Real Owner Repair Stories

• Reddit user on r/MechanicAdvice (Vehicle unspecified, but experiencing P0352) — Intermittent shuddering/misfiring, which then goes away. The issue is reproducible when starting the engine 'luke warm' (after sitting for about an hour).
  ❌ Tried (didn't work) Replaced ECU (PCM), Replaced coil pack, Replaced spark plugs
  ✅ What actually fixed it The final resolution was not posted, but a likely cause suggested by another user was a nicked wire or corroded connection in the harness between the coil and the ECU, or a defective new coil. This highlights that even after replacing all common components, the fault can persist due to wiring issues.
• YouTube video by STANHOPE AUTO REPAIR CENTRE (2017 Ford C-Max 1.6L Petrol (European model, but demonstrates a relevant failure mode)) — Heavy misfiring, P0352 code present.
  ❌ Tried (didn't work) Another garage had diagnosed a faulty ECU.
  ✅ What actually fixed it The locking clips on the main ECU/PCM connectors were broken and the connector was secured with a weak zip tie. Vibrations caused the connector for the ignition coil circuits to partially back out, creating an open circuit. Securing the connector properly resolved the P0352 code.

OEM Part Supersession History

• 4M5Z-12029-A, 4M5Z-12029-BA, 4M5Z-12029-BB → 4M5Z-12029-BC (also known as Motorcraft DG-541) — Part has been revised multiple times by Ford for improved reliability and performance.
  Heads up: The latest part number, 4M5Z-12029-BC, replaces all previous versions and is the recommended service part.

Model Year Variations Within This Range

• 2016-2018: For the 2016 model year, Ford replaced the often-criticized MyFord Touch infotainment system with the much-improved SYNC 3 system, which includes Apple CarPlay and Android Auto support.
• 2015-2018: Models from 2015 and later are generally considered more reliable, with reports of fewer transmission issues compared to the 2013-2014 models.
• 2017: The trim levels were simplified, with the 'Titanium' trim replacing the previous 'SEL' as the top-tier option.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Shifter Cable Bushing Failure 🔴 High — Extremely common across millions of Ford vehicles, including all 2013-2018 C-Max models. The bushing degrades, causing a disconnect between the shifter and transmission, potentially leading to a rollaway. (Ref: Recall 22V-413 (NHTSA ID) / Ford Recall 22S43.)
• 12V Battery Parasitic Drain 🟠 Medium — A well-documented issue, particularly on earlier 2013-2016 models. The 12V battery can be drained overnight by software glitches, often related to the SYNC infotainment system or other modules failing to enter sleep mode. (Ref: TSB 25-2081 and SSM 46368 address software updates to fix battery drain conditions.)
• Water Leaks into Hatch/Boot Area 🟡 Low — Many owners report water pooling in the spare tire well. Common entry points are failed seals around the taillight assemblies, roof rack mounting points, or body seams under the hatch trim.
• Transmission Grinding/Thumping Noise 🟠 Medium — Affects vehicles built on or before August 15, 2015. A noise from the HF35 transmission may occur. (Ref: TSB 17-0039.)
• Power Steering Failure 🔴 High — A number of complaints exist for intermittent or total failure of the electronic power steering assist, which can make the vehicle very difficult to steer. (Ref: NHTSA complaints exist, but no widespread recall was issued for the C-Max specifically.)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this repair, using a used part is generally not recommended. The primary cause, the ignition coil, is a maintenance item that degrades with heat and time. A used coil has an unknown remaining lifespan and may fail soon after installation.

Donor-vehicle mileage cap: roughly under 40000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• If a used coil must be sourced, choose one from a low-mileage, late-model-year donor vehicle (2016-2018).
• Inspect the plastic housing for any cracks, melting, or signs of heat stress.
• Ensure the connector pins are clean, straight, and free of corrosion.
• Avoid coils that have any oil residue on the boot, as this may indicate a valve cover leak on the donor car, which can damage the coil.

OEM-only on this vehicle (don't cheap out):

• While not strictly 'OEM-only', using a Motorcraft ignition coil is highly recommended for longevity. Many forum users report premature failure from no-name, low-cost aftermarket coils.

Aftermarket brands forum-validated for this vehicle:

• NGK
• Bosch
• DENSO

Brands owners have reported issues with on this vehicle:

• Unnamed or 'white-box' ignition coils sold on online marketplaces are a gamble and frequently have high failure rates.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0351 — Ignition Coil 'A' (Cylinder 1) Circuit Malfunction; often appears during diagnosis if a faulty coil is swapped from cylinder 2 to cylinder 1 to confirm failure.
• P0353 — Ignition Coil 'C' (Cylinder 3) Circuit Malfunction; middle cylinders #2 and #3 are anecdotally reported to fail more frequently due to heat exposure.
• P0354 — Ignition Coil 'D' (Cylinder 4) Circuit Malfunction; can appear alongside P0352 if there is a broader issue with the PCM or wiring harness.
• P0302 — Cylinder 2 Misfire Detected; this is a mechanical misfire code that frequently accompanies the circuit-specific P0352 code when a coil fails.

Frequently Asked Questions