Faulty ignition coil or coil driver for the affected cylinder, pulling the control line low; Damaged wiring to the coil control circuit, such as a short to earth or chafed insulation; Corroded, loose or contaminated coil connector terminals; Poor supply or earth to the coil, giving an incorrect control signal level; Fault in the ECU output driver for that coil control channel; Water ingress into the coil wells or harness connectors.

P036B

Ignition G Control Signal Circuit Low.

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
6B: FaultThe specific fault in that area

What it means

P036B means the engine control unit has seen a low voltage or a signal that is stuck low on the control circuit for ignition coil 'G'. This is the signal the ECU sends to the coil or its built-in driver to fire the spark. Which cylinder 'G' refers to depends on the engine and the manufacturer's coil labelling, so check model-specific data.

Symptoms

Engine misfire, rough running or hesitation, mainly under load
Malfunction indicator lamp on, possibly flashing during a heavy misfire
Hard starting or an extended cranking time
Loss of power and poor fuel economy
Smell of unburnt fuel from the exhaust
Misfire codes stored alongside P036B for the affected cylinder

Possible causes

Faulty ignition coil or coil driver for the affected cylinder, pulling the control line lowlikely
Damaged wiring to the coil control circuit, such as a short to earth or chafed insulationlikely
Corroded, loose or contaminated coil connector terminalslikely
Poor supply or earth to the coil, giving an incorrect control signal levelpossible
Fault in the ECU output driver for that coil control channelrare
Water ingress into the coil wells or harness connectorspossible

How to diagnose

Read all stored and pending codes and note the freeze frame data (engine load, rpm, temperature) to see when the fault occurred
Check for misfire counts on the cylinder served by coil 'G' using live data, and confirm which cylinder that is for this engine
Visually inspect the coil connector, harness routing and nearby components for chafing, heat damage, oil or water contamination
Check the coil connector pins for corrosion, looseness or spread terminals
Swap the suspect coil with a neighbouring cylinder, clear the codes and see whether the fault or misfire follows the coil
Check the coil supply voltage and earth with a multimeter, following the manufacturer's wiring diagram
Test the control wire for continuity and for a short to earth between the coil connector and the ECU connector
Check the spark plug in that cylinder for wear, fouling or the wrong gap, as this can stress the coil

How to fix

Replace the faulty ignition coil, and check the spark plug at the same time
Repair or replace damaged wiring in the control circuit, then insulate and secure it properly
Clean or replace corroded connectors and terminals, and fix any source of water or oil ingress
Restore a poor power or earth connection to the coil
Replace or repair the ECU only after all wiring and coil faults are ruled out and the manufacturer's procedure confirms a driver fault

Can I keep driving?

Medium severity

Avoid driving the car further than necessary, as a misfire can overheat and damage the catalytic converter. If the warning lamp flashes, stop driving and have it checked promptly.

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