P0352 on 2003-2009 Toyota 4Runner 4.7L V8: Ignition Coil 'B' Circuit Fixes

What's Unique About the 2003-2009 Toyota 4Runner

The 4.7L 2UZ-FE V8 is a very reliable engine, and this code is not indicative of a major design flaw. Like any vehicle, the individual coil-on-plug ignition coils are wear-and-tear items that eventually fail with age and heat cycles. The issue is typically isolated to a single failed coil and is not usually a sign of a larger systemic problem on this platform. Access to the coils, particularly cylinder #2 on the passenger side, is excellent, making this a much easier repair than on many other V-type engines.

Symptoms You May Notice

• Check Engine Light is on
• Engine misfire, which may feel like a stumble or hesitation during acceleration
• Rough or unstable idle
• Reduced engine power and responsiveness
• In severe cases, the Check Engine Light may flash, indicating a catalyst-damaging misfire
• Slight decrease in fuel economy

Most Likely Causes

1. Failed Ignition Coil (Cylinder #2) 🔴 High Probability → Shop Ignition Coil Ignition coils are a common wear item on most modern engines due to constant exposure to high heat and voltage. They are not a specific weak point on the 2UZ-FE, but failure after 100,000+ miles is expected.
   How to confirm: The easiest way to confirm is to swap the ignition coil from cylinder #2 with another cylinder (e.g., cylinder #4). Clear the codes and drive. If the code changes to P0354 (for cylinder #4), the coil is definitively bad. This is a widely accepted and effective diagnostic step. 🎬 Watch: How to diagnose and replace bad 4.7L V8 coils
   Typical fix: Replace the faulty ignition coil. It is held in by a single 10mm bolt. 🎬 See this step-by-step ignition coil replacement walkthrough It's also a good time to inspect the spark plug.
   Est. part cost: $40-$90
2. Damaged Wiring or Connector ⚪ Low Probability The plastic connector clips can become brittle over time from engine heat and may break during service, leading to a poor connection. Rodent damage to the wiring harness is also a possibility.
   How to confirm: Visually inspect the wiring harness and connector for cylinder #2's ignition coil. Look for cracks, melted plastic, corrosion on the pins, or loose wires. If the coil swap test did not move the code, the wiring is the next suspect.
   Typical fix: If the connector is broken, replace it with a new pigtail connector. If wiring is damaged, repair the affected section.
   Est. part cost: $10-$25 for a pigtail
3. Worn or Fouled Spark Plug ⚪ Low Probability → Shop Spark Plug While a bad spark plug typically causes a misfire code (P0302), a plug with an excessive gap can put extra strain on the ignition coil, leading to its premature failure and potentially triggering the P0352 circuit code.
   How to confirm: Remove the spark plug from cylinder #2 and inspect its condition. Look for heavy carbon deposits, oil fouling, or a worn-down electrode.
   Typical fix: Replace the spark plug. It is recommended to replace all 8 spark plugs if they are near the end of their service interval.
   Est. part cost: $5-$15 per plug

Rare But Worth Checking

• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is extremely rare. The ECM's internal driver for the ignition coil can fail, but this should only be considered after all other possibilities (coil, plug, wiring) have been exhaustively ruled out.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0352 is present.
2. Locate cylinder #2 on the 4.7L V8. When facing the engine from the front of the vehicle, the passenger side bank contains cylinders 2, 4, 6, and 8, from front to back. The driver's side has 1, 3, 5, 7. Cylinder #2 is the front-most cylinder on the passenger side.
3. Inspect the ignition coil's electrical connector and nearby wiring for any visible damage, corrosion, or looseness.
4. Swap the ignition coil from cylinder #2 with the coil from cylinder #4 (the next one back on the passenger side). This is a simple and effective test.
5. Clear the trouble codes with the scanner.
6. Start the engine and go for a short drive to see if the Check Engine Light returns.
7. Re-scan for codes. If the code is now P0354, the ignition coil you moved is faulty and needs to be replaced.
8. If the code P0352 returns, the problem lies in the wiring to cylinder #2 or, rarely, the ECM.
9. At this point, inspect the spark plug in cylinder #2. If it is old or fouled, replace it.
10. If the problem persists, use a multimeter to check for 12V power and good ground at the coil connector for cylinder #2. For advanced diagnosis, use an oscilloscope to check for the IGT (trigger) and IGF (confirmation) signals from the ECM.

Parts You'll Likely Need

• Ignition Coil (OEM #90919-02230) — This is the most common failure point for a P0352 code. The internal windings of the coil fail over time, causing a circuit fault.
  Trusted brands: Denso (OEM), NGK, Bosch, Standard Motor Products
  OEM price range: $70-$110
  Aftermarket price range: $40-$80
• Ignition Coil Connector Pigtail (OEM #90980-11885) — The plastic locking tab on the original connector often becomes brittle with age and can break when disconnecting the coil, leading to a loose connection.
  Trusted brands: Dorman, Standard Motor Products (S-755), ACDelco
  OEM price range: $15-$30
  Aftermarket price range: $10-$20

Related Codes That Often Appear With This One

• P0302 — P0302 means 'Cylinder 2 Misfire Detected'. The P0352 circuit fault is the direct cause of the misfire 🎬 Watch: P0352 code and Cylinder 2 coil problems explained, so these codes almost always appear together.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Cracked Exhaust Manifolds 🟠 Medium — Very common, often occurs after 80,000 miles. Presents as a ticking noise, especially when the engine is cold, which may disappear as the metal expands with heat.
• Secondary Air Injection System (SAIS) Failure 🔴 High — Common on 2005+ models. The air pump, located under the intake manifold, fails due to moisture or foam filter degradation, sending debris into the switching valves. This is an expensive repair ($1500-$3500) that will put the vehicle in 'limp mode'. Many owners opt for an aftermarket bypass kit. (Ref: TSB T-SB-0230-12 Rev1 (for related codes))
• Frame Rust 🔴 High — Widespread issue, particularly in regions that use road salt. Unlike the Tacoma and Tundra of the same era, the 4th Gen 4Runner was not included in Toyota's frame replacement program, despite class-action lawsuits. Thorough underbody inspection is critical before purchase.
• Seized Brake Calipers 🟠 Medium — Common across all years. The front brake caliper pistons are prone to seizing, causing brake drag, pulling to one side, and premature pad/rotor wear.
• Timing Belt Replacement (Interference Engine) 🔴 High — This is a critical maintenance item, not a failure. The 2UZ-FE is an interference engine, and the timing belt must be replaced every 90,000-100,000 miles. Failure to do so will result in catastrophic engine damage.

Real Owner Stories

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

Related OBD-II Codes

• P0354 — This code indicates an ignition coil primary/secondary circuit malfunction for cylinder #4; it is the code that will appear if you swap a faulty cylinder #2 coil into the cylinder #4 position during diagnosis.
• P0302 — A cylinder #2 misfire code that often accompanies P0352 or can be caused by the same fouled spark plug or failed coil.
• P0351 — Ignition coil circuit malfunction for cylinder #1; shares the same root causes (coil failure, brittle connectors) as P0352 on the 2UZ-FE engine.
• P0353 — Ignition coil circuit malfunction for cylinder #3; part of the same P035x series of ignition system faults common on high-mileage 4.7L engines.

Frequently Asked Questions