P0362
Ignition Coil L Primary/Secondary Circuit MalfunctionP0362 is a generic OBD-II powertrain diagnostic trouble code: Ignition Coil L Primary/Secondary Circuit Malfunction. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0362 means
P0362 is a generic OBD-II fault code indicating a malfunction in the primary or secondary circuit of ignition coil "L". Coil "L" is the 12th in the alphabetical designator sequence and is therefore only present on V12 engines, where it serves cylinder 12. The PCM drives every coil-on-plug unit directly and monitors the driver circuit for proper current build-up and collapse on each firing event. When the module detects an open circuit, a short to battery voltage, or a short to ground on the coil "L" driver line, it stores P0362 and illuminates the MIL. Cylinder 12 ceases to fire, allowing unburned fuel to pass into the exhaust system; prolonged operation in this condition can destroy catalytic converters and oxygen sensors. The companion misfire code P0312 (cylinder 12 misfire) is virtually always stored at the same time. As with coils "J" and "K", coil "L" is often located in a thermally harsh position within the V12 engine bay, making heat-related connector and insulation failures a notable cause in addition to coil body failure.
Common causes
Most-frequently reported root causes when P0362 is logged.
-
1
Failed ignition coil "L" — internal open or short in the primary or secondary winding
-
2
Short to battery voltage on the PCM driver wire for coil "L"
-
3
Short to ground on the coil "L" control circuit
-
4
Open circuit in the driver wire or 12 V supply feed to coil "L"
-
5
Corroded, spread, or damaged terminals in the coil "L" electrical connector
-
6
Heat-degraded wiring insulation in the cylinder 12 area of the engine bay
-
7
PCM coil driver failure for cylinder 12 (rare; confirm only after ruling out coil and circuit faults)
Symptoms drivers notice
How to diagnose P0362
A typical diagnostic flow when this code is present.
-
1
Retrieve all DTCs with a scan tool; P0312 alongside P0362 confirms cylinder 12 is not firing and correlates the fault to coil "L"
-
2
Perform a thorough visual inspection of coil "L", its boot, wiring, and connector — check specifically for carbon tracking, cracked boot, corrosion, and heat damage
-
3
Swap coil "L" with a coil from a known-good cylinder and clear codes; if misfire and circuit code migrate to the new location, coil "L" is faulty
-
4
If the fault remains on cylinder 12 after the coil swap, check for 12 V supply and a valid PCM trigger signal at the coil "L" connector using a test light or oscilloscope during cranking
-
5
Measure primary winding resistance (typically 0.4–2 Ω) and secondary winding resistance (typically 6,000–15,000 Ω) and compare to manufacturer specification
-
6
Test driver wire continuity and insulation resistance from the coil connector back to the PCM; repair any short or open found in the harness
-
7
If coil, connector, and harness all pass testing, verify the PCM coil driver output waveform and consider PCM replacement only as a confirmed last resort
Related powertrain codes
Frequently asked questions
Why is coil "L" only found on V12 engines?
OBD-II uses a simple alphabetical scheme: coil "A" = cylinder 1, "B" = cylinder 2, and so on. Coil "L" is the 12th letter, so it only exists on engines with at least 12 cylinders. The code will never appear on 4-, 6-, 8-, or 10-cylinder vehicles.
Can I drive the car with P0362 active?
Only for the shortest distance necessary to reach a repair facility. A dead cylinder 12 sends unburned fuel into the catalytic converter, which can overheat and be permanently damaged within a short drive. Many PCMs activate a fuel-cut catalyst-protection strategy on the dead cylinder, which causes a noticeable power reduction and roughness.
How does P0362 relate to P0312?
P0312 is a cylinder 12 misfire count code — it fires when the PCM counts enough misfires on that cylinder. P0362 is a circuit-level code — it fires when the PCM detects an electrical fault on the coil driver line regardless of misfire count. Both usually appear together when coil "L" fails, but P0362 can occasionally appear alone if the circuit fault is intermittent and the cylinder sometimes fires normally.
Could a bad spark plug cause P0362?
A severely fouled or shorted plug can overload the coil secondary and in some cases cause a driver-circuit fault. However, P0362 primarily flags the electrical control circuit detected by the PCM. If swapping the coil does not move the fault, inspect the cylinder 12 spark plug and coil boot for carbon tracking before proceeding to wiring and PCM diagnosis.
Disabling P0362 in software
RaceTune can permanently disable P0362 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P0362 in your scan?
Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.
Upload your file