Faulty ignition coil F, with an internal open circuit in the primary winding or integrated driver; Damaged, chafed or broken wiring in the coil F control signal circuit; Corroded, loose or pushed-out pins in the coil connector or engine control unit connector; Open circuit in the coil power supply or earth feed affecting the coil F circuit; Water ingress or heat damage to the harness or coil connector; Internal fault in the engine control unit driver for coil F.

P035D

Ignition F Control Signal Circuit/Open.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
3: AreaIgnition system or misfire
5D: FaultThe specific fault in that area

What it means

P035D is the generic code for an open circuit in the control signal circuit for ignition coil F, which is normally the sixth coil in the engine's firing arrangement. The engine control unit monitors the coil driver circuit and has detected an open circuit, meaning the trigger signal is not reaching the coil or the circuit is not completing as expected. Which cylinder 'F' refers to depends on the manufacturer and engine, so check the model-specific data.

Symptoms

Engine misfire, especially under load
Rough idle or shaking at rest
Flashing or steady engine warning light
Loss of power and poor acceleration
Increased fuel consumption
Hesitation or stumbling when pulling away

Possible causes

Faulty ignition coil F, with an internal open circuit in the primary winding or integrated driverlikely
Damaged, chafed or broken wiring in the coil F control signal circuitlikely
Corroded, loose or pushed-out pins in the coil connector or engine control unit connectorlikely
Open circuit in the coil power supply or earth feed affecting the coil F circuitpossible
Water ingress or heat damage to the harness or coil connectorpossible
Internal fault in the engine control unit driver for coil Frare

How to diagnose

Read all stored and pending codes and note any misfire codes for the cylinder served by coil F; review the freeze frame data for engine speed, load and temperature when the fault set.
Confirm from model-specific data which cylinder coil F serves on this engine and where the coil sits.
Visually inspect the coil F connector, harness and surrounding wiring for chafing, heat damage, oil contamination, corrosion or water ingress.
Disconnect the connector and check the pins for looseness, spreading or corrosion, then reconnect firmly and see whether the code returns after clearing.
Swap coil F with a known good coil from another cylinder and see whether the code or misfire follows the coil.
With the ignition off and the control unit connector disconnected where the procedure allows, test the control signal wire for continuity and for shorts to earth or supply, following the wiring diagram.
Check the coil power supply and earth at the connector with a multimeter against the manufacturer's specification.
Use a scan tool or oscilloscope to watch the control signal during cranking to confirm the control unit is sending a trigger pulse.

How to fix

Replace ignition coil F if it fails the swap test or electrical checks.
Repair or replace damaged wiring in the control signal circuit, using proper soldered or crimped and sealed repairs.
Clean, repair or replace corroded or damaged connector terminals and secure the connector properly.
Restore a faulty power or earth supply to the coil circuit.
Check the spark plug for the affected cylinder and replace it if worn or fouled, as this can shorten coil life.
Only after all wiring and the coil are proven good, diagnose and repair or replace the engine control unit as directed by the manufacturer.

Can I keep driving?

Medium severity

Short, gentle journeys are possible, but avoid heavy loads and high revs. A flashing warning light indicates a severe misfire that can overheat and damage the catalytic converter, so stop driving and get it checked promptly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.