Damaged, corroded or loose connector at the ignition coil; Open circuit or high resistance in the coil control signal wire between the control unit and the coil; Faulty ignition coil or integrated driver module; Missing or poor power supply or earth to the coil, where the coil has its own driver; Wiring chafed or damaged by heat, vibration or rodent activity; Faulty engine control unit output driver.

P035A

Ignition E 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
5A: FaultThe specific fault in that area

What it means

P035A is the generic code for an open circuit in the control signal for ignition coil E. The engine control unit commands the coil driver and monitors the circuit, and it has detected no current path or an open condition on that signal. Which cylinder coil E refers to depends on the manufacturer and engine, so check the wiring diagram for the vehicle.

Symptoms

Engine misfire, especially under load or acceleration
Rough or unstable idle
Malfunction indicator lamp on, possibly flashing during a severe misfire
Hesitation or loss of power
Hard starting or a no-start on some engines
Increased fuel consumption

Possible causes

Damaged, corroded or loose connector at the ignition coillikely
Open circuit or high resistance in the coil control signal wire between the control unit and the coillikely
Faulty ignition coil or integrated driver modulelikely
Missing or poor power supply or earth to the coil, where the coil has its own driverpossible
Wiring chafed or damaged by heat, vibration or rodent activitypossible
Faulty engine control unit output driverrare

How to diagnose

Read all stored codes and freeze frame data, noting engine load, speed and temperature when the fault set, and check for related misfire codes
Identify which cylinder coil E is on this engine using the wiring diagram or service information
Visually inspect the coil connector, terminals and harness for corrosion, bent pins, heat damage and chafing
Clear the code and see if it returns, wiggling the harness and connector while the engine runs to look for an intermittent fault
Check the coil power supply and earth connections with a multimeter against the specified values
Check the control signal wire for continuity and for short to earth or supply between the coil connector and control unit connector with the battery disconnected
Swap the suspect coil with one from another cylinder and see whether the fault follows the coil or stays with the circuit
Check the control unit output signal with an oscilloscope or suitable tester if the wiring and coil test good

How to fix

Repair or replace the damaged wiring section and secure it away from heat and sharp edges
Clean or replace the corroded or damaged connector and terminals
Replace the faulty ignition coil, and check the spark plug condition at the same time
Restore the coil power or earth supply by repairing the circuit or related fuse or relay fault
Replace or repair the engine control unit only after the wiring and coil have been proven good

Can I keep driving?

Medium severity

Short, gentle journeys are possible, but the car should be fixed soon. A misfire can overheat the catalytic converter and cause further damage, so avoid heavy loads and stop driving if the warning lamp flashes.

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