Faulty ignition coil G, where the internal primary winding or control electronics have failed; Damaged or chafed wiring in the ignition control signal circuit for coil G, causing a short to ground; Corroded or loose electrical connector at coil G or at the powertrain control module; Failed ignition control module or driver inside the powertrain control module that commands coil G; Poor engine ground or a voltage drop on the coil power feed that affects only that coil circuit; Aftermarket alarm or remote starter wiring that has tapped into the ignition coil circuit and created a low-resistance path

DTC codes / P03xx · Ignition system and misfire / P036B

P036BIgnition G Control Signal Circuit Low

Q: What does code P036B mean?

Ignition G Control Signal Circuit Low. P036B indicates that the powertrain control module has detected a low-voltage condition on the ignition control signal circuit for coil G, which is one of the individual ignition coils in a distributorless ignition system. The computer expects to see a switching signal that toggles between high and low voltage as it commands the coil to fire, but the feedback or command line is stuck below the normal threshold, so the coil may not be firing at all.

P036B indicates that the powertrain control module has detected a low-voltage condition on the ignition control signal circuit for coil G, which is one of the individual ignition coils in a distributorless ignition system. The computer expects to see a switching signal that toggles between high and low voltage as it commands the coil to fire, but the feedback or command line is stuck below the normal threshold, so the coil may not be firing at all.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or a noticeable miss at idle that may smooth out at higher RPM
Engine misfire under load, such as during acceleration or climbing a hill
Reduced power and poor fuel economy due to a dead cylinder
Shaking or vibration felt through the steering wheel or seat
In some cases, the engine may enter limp mode or flash the check engine light if the misfire is severe

Common causes, most likely first

Faulty ignition coil G, where the internal primary winding or control electronics have failed
Damaged or chafed wiring in the ignition control signal circuit for coil G, causing a short to ground
Corroded or loose electrical connector at coil G or at the powertrain control module
Failed ignition control module or driver inside the powertrain control module that commands coil G
Poor engine ground or a voltage drop on the coil power feed that affects only that coil circuit
Aftermarket alarm or remote starter wiring that has tapped into the ignition coil circuit and created a low-resistance path

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm the fault is current and not history
Perform a visual inspection of coil G, its connector, and the harness for damage, corrosion, or loose pins
Swap coil G with a known-good coil from another cylinder and see if the misfire or code moves with the coil
Use a digital multimeter to check the control signal circuit for a short to ground with the key on and engine off
Back-probe the control signal wire at the powertrain control module and verify the command signal switches between low and high voltage
Check the coil power feed and ground circuit for excessive voltage drop under load
If the signal circuit and coil are good, test or replace the powertrain control module as the last step

What the coil G signal test really shows

A low signal code often means the coil driver inside the powertrain control module has failed, not the coil itself, so swapping coils first prevents an unnecessary part replacement.
The control signal wire can be shorted to ground by a pinched harness under the intake manifold or near a sharp bracket, which is easy to miss during a visual inspection.
A failing ignition coil can sometimes test good with an ohmmeter because the fault only appears when the coil is hot or under load, so a swap test is more reliable than a resistance check alone.
This code does not always mean the coil is dead; a poor ground at the engine block can cause a low signal on one coil circuit while other coils continue to fire normally.
Aftermarket remote start or alarm installations that splice into ignition wiring are a common hidden cause of low signal codes on one coil.

Can I keep driving with P036B?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration or sustained high-speed driving because the unburned fuel from the dead cylinder can overheat and damage the catalytic converter. If the check engine light is flashing, stop driving and have the vehicle towed.

Tools that help

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