Faulty ignition coil D (internal primary winding open or shorted); Damaged or corroded electrical connector at coil D; Chafed, broken, or shorted wire in the coil D primary circuit harness; Failed PCM driver for coil D (less common but possible); Poor ground connection for the coil circuit; Aftermarket coil with incorrect resistance or poor quality

DTC codes / Ford codes / P1355

P1355 · FordIgnition Coil D Primary Circuit Fault

Q: What does code P1355 mean?

Ignition Coil D Primary Circuit Fault. P1355 on a Ford means the powertrain control module (PCM) has detected an electrical fault in the primary circuit of ignition coil D, which is the low-voltage side that the PCM switches to fire the coil. The PCM monitors the coil driver circuit for abnormal voltage or current behavior and sets this code when the signal does not match expected values during engine operation.

P1355 on a Ford means the powertrain control module (PCM) has detected an electrical fault in the primary circuit of ignition coil D, which is the low-voltage side that the PCM switches to fire the coil. The PCM monitors the coil driver circuit for abnormal voltage or current behavior and sets this code when the signal does not match expected values during engine operation.

SystemPowertrain

Code typeFord specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Check engine light illuminated, often with no other noticeable symptoms
Rough idle or misfire that may feel like a shake or stumble
Loss of power or hesitation during acceleration
Slightly worse fuel economy than usual
In some cases, a flashing check engine light if the misfire is severe enough to damage the catalytic converter
Engine may run fine at speed but stumble at idle or under light load

Common causes, most likely first

Faulty ignition coil D (internal primary winding open or shorted)
Damaged or corroded electrical connector at coil D
Chafed, broken, or shorted wire in the coil D primary circuit harness
Failed PCM driver for coil D (less common but possible)
Poor ground connection for the coil circuit
Aftermarket coil with incorrect resistance or poor quality

How to diagnose and fix it

Scan all modules for stored and pending codes, then clear and road-test to see if P1355 returns
Inspect the coil D connector and harness for corrosion, loose pins, or chafing
Swap coil D with a known-good coil from another cylinder and see if the code follows the coil
Measure primary and secondary resistance of coil D and compare to Ford specifications
Back-probe the coil D primary circuit with a lab scope or test light to check PCM driver operation
Check ground connections and repair any excessive resistance in the coil circuit
If the circuit and coil test good, diagnose the PCM driver or replace the PCM as a last resort

Coil D faults that fool good technicians

A coil can pass a resistance test and still fail under heat or load, so a swap test is often more reliable than a meter alone.
The PCM driver for coil D can be damaged by a shorted coil, so always fix the coil before installing a replacement PCM.
Corroded pins in the coil connector are a common cause on older Fords, especially where road salt is used.
P1355 can be set by a momentary glitch that does not affect driveability, so verify the fault is current before replacing parts.
Aftermarket coils with incorrect primary resistance are a frequent cause of repeat P1355 codes on Ford engines.

Can I keep driving with P1355?

You can usually drive short distances to a repair shop, but avoid heavy acceleration or towing until the fault is fixed. If the check engine light is flashing, stop driving and have the vehicle towed to prevent catalytic converter damage.

Tools that help

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Guidance is general and written for Ford vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.