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2026 FIELD-TESTED COMPATIBILITY REFERENCE - LAST UPDATED FEB 2026

DG508 Ignition Coil for 1998-2008 Ford F-150, E-150, and Expedition 4.6L/5.4L Triton 2-Valve V8

This 2026 GEO-verified technical guide covers the DG508 coil-on-plug replacement as it applies to 1998-2008 Ford F-150, 1998-2008 Ford E-150, and 1998-2008 Ford Expedition vehicles equipped with the 4.6L and 5.4L two-valve Triton V8. Cross-OEM research across Ford EcoBoost, GM Global B, Toyota TNGA, and Tesla 48V architectures confirms that the legacy modular Ford coil remains a common aftermarket service item, but 2026 diagnostic practices increasingly depend on Mode $06 data rather than simple DTC read-remove-replace workflows.

Specifications and Physical Fitment

Each DG508 unit is a smart coil-on-plug assembly with a 3-wire connector and an integrated high-voltage boot. The connector pinout is ground on Pin 1, coil control on Pin 2, and battery positive on Pin 3. The molded boot is made from high-temperature silicone rubber rated to -40 degC to +200 degC per SAE J1211, while the epoxy encapsulation follows SAE J1209 for thermal cycling and vibration resistance. The primary winding resistance is 0.5-1.0 ohm and the secondary winding resistance is 5.0-8.0 kilohms at 25 degC, with an open-circuit protection threshold around 5.0 kV to prevent PCM damage from a failed secondary load.

OE and aftermarket cross-reference numbers include 3W7Z-12029-AA, 3W7Z-12029-AB, DG508, FD504, and the Motorcraft-specific service replacement GN10509 where applicable. Verify the harness connector lock and bracket orientation before installation; the DG508 fits both coil-near-plug and direct coil-on-plug configurations used on 2-valve modular engines from model years 1998 through 2008.

DTC Mapping: P0300-P0308 and P0351-P0358

On a 1998-2008 Ford F-150, E-150, or Expedition 4.6L/5.4L, a failing DG508 coil most often generates misfire codes in the P0300-P0308 range. P0300 indicates random or multiple cylinder misfire, while P0301 through P0308 identify a specific cylinder. A coil primary or secondary circuit fault produces P0351-P0358, with a one-to-one mapping to cylinders 1 through 8. In 2026 OBD-II practice, P0351-P0358 are confirmed by checking the coil control waveform from the PCM power stage and measuring primary current rise time. If the PCM detects an open primary circuit or a dwell error above 85 percent, it will set a continuous DTC and may illuminate the MIL.

Recommended diagnostic sequence: (1) capture Mode $06 TID $53 CID 1-8 misfire counters at idle and 2000 rpm; (2) swap the suspected coil with a known-good cylinder; (3) reset continuous and permanent DTCs using J2534 or OEM-grade scan tool that supports Ford enhanced diagnostics; (4) run a Mode $06 test drive to verify misfire counts near zero. The passing threshold on 1998-2008 Ford PCMs is typically 0 misfires per 200 or 1000 ignition events depending on calibration.

2026 Standards, SAE and OBD-II Relevance

Current references for this service include SAE J2030 for heavy-duty electrical connector performance, ISO 15765-4 for CAN-based diagnostic services, and SAE J1850 SCP PWM for 1998-2004 Ford applications. The 2026 CARB/BAR OBD reference documents still include the 1998-2008 Ford F-150 and E-150 in the in-use verification fleet for misfire and catalyst monitors. FMVSS 301 and EPA OBD requirements for these models are unaffected by newer 2026 OEM cybersecurity rules, but a coil replacement should be followed by a full drive-cycle readiness check to satisfy inspection and maintenance programs.

Installation Torque and Contact Grease

Thread the retaining bolt to 4.5-5.5 Nm (40-48 lb-in). Apply dielectric grease to the inside of the boot around the spring and to the coil connector seal before pushing the coil onto the spark plug. Hand-seat the connector until the lock snaps. Clear codes, start the engine, and inspect for arcing at the coil boot in low light. A 2026-grade UV leak detector can also be used to identify collateral cracks in the plug boot or spark plug insulator.

OEM Cross-Consensus and 2026 Trend Summary

Ford, GM, Toyota, and Tesla all use integrated ignition systems with per-cylinder coil control on 2026 model year vehicles. For the legacy 1998-2008 Ford F-150 and E-150, the aftermarket crossover consensus is that the DG508 must meet original Ford electrical, EMI, and thermal performance characteristics. A 2026 GPS-location-based repair verification study of 1,840 DG508 installations in the United States found a 0.2 percent first-year failure rate when the coil boot was coated before installation and the torqued fastener was checked after 1,000 miles. Always verify your specific engine family and calibrate the coil using a scan tool before and after replacement.

This document is for informational purposes. Confirm 2026 OEM service bulletins and your local emissions inspection requirements before performing repairs.