P3486 code definition
When a P0346 trouble code is stored it signals that the Powertrain Control Module (PCM) has detected a problem in cylinder 11 associated with performance. Other trouble codes that might show up as well include a P3481, P3482, P34883, P34884, P34885, P34887, and P3488 trouble code.
What the P3486 code means
The way a V12 engine works is that when not under heavy load, or during light driving conditions, the engine disables some of the cylinders. The PCM does this using data received from the mass airflow sensor, with the PCM then instructing certain cylinders to shut down. This is called variable displacement, which is accomplished with reduced oil flow to the valve lifters of the cylinders in question and the stopping of the intake valves and exhaust filters from opening. In the case of a V12, up to six cylinders can be shut down in this way. When the PCM detects a fault in the reduced valve mode, a P03486 trouble code is stored and the Check Engine light illuminates.
What causes the P3486 code?
In addition to a defective throttle position sensor, a P3486 code has some other causes. These include a low oil level in the engine, reduced oil pressure on the lifters, or restricted oil flow in the engine oil passages. Some other causes include a defective cylinder deactivation solenoid, intake control manifold absolute pressure sensor, mass air flow sensor, lifters, or wiring and connector problems within the cylinder deactivation solenoid harness or cylinder deactivation solenoid circuit.
What are the symptoms of the P3486 code?
In addition to a stored code and a lit Check Engine light, symptoms of a P3486 trouble code include a vibrating engine, lowered fuel efficiency, and sluggish acceleration. The storage of a P3486 trouble code usually leads to the disabling of variable valve timing until the problem is fixed and the code is cleared.
How does a mechanic diagnose the P3486 code?
In order to clear a P3486 trouble code, a mechanic needs to perform a diagnostic using an advanced scanner, a manual pressure gauge, air compressor, and a digital volt/ohm meter. The mechanic must also perform the following steps when diagnosing the P3486 trouble code:
- First off, the mechanic needs to check the oil level, and if it's at a low level, they should repair any leaks before filling the oil to a normal level.
- Next, inspect all wiring, connectors, and components associated with the cylinder 11 exhaust valve control system.
- Once all faulty wiring, connectors, and components have been repaired, the mechanic should clear the code and operate the vehicle to see if the code returns.
- If the trouble code returns, the mechanic should test the voltage and ground signal of the throttle position sensor with the digital volt/ohm meter to see if it is faulty.
- If there is no voltage or ground signal at the throttle position sensor, the mechanic should disconnect the PCM and any related modules before testing the continuity of the throttle position sensor with the battery ground.
- The mechanic should also check the voltage, ground, and continuity of the cylinder deactivation solenoid, intake control manifold absolute pressure sensor, and the mass airflow sensor with the digital volt/ohm meter to see if they are bad.
- The mechanic can also perform a valve leak down test to determine pressure levels within the cylinder. The mechanic should use a manual pressure gauge and pump compressed air into the cylinder via the spark plug hole, comparing their findings to the manufacturer's specifications.
- In the case of a bad lifter in cylinder 11, the mechanic has to remove the valve cover. This could include having to remove the fuel line, vacuum hoses, throttle linkage, sensor wires, and any other components impeding the removal of the valve covers.
- Using a feeler gauge, the mechanic should test the clearance of the lifter while the vehicle is in operation.
- After reinstalling the valve cover and all of the engine components, the mechanic should clear the code and test the vehicle to see if the code returns.
Common mistakes when diagnosing the P3486 code
Mechanics often forget to clear the oil passageways of buildup or sludge when diagnosing and treating a P3486 trouble code. The clogged passageway can cause the engine oil pressure to fall and contribute to poor engine operation, especially with the lifters in the cylinder.
How serious is the P3486 code?
While not as serious as other stored codes, a P3486 trouble code, if left unattended, can do irreparable harm to your vehicle's engine, especially in the case of a bad lifter. Even if your engine components are not damaged, you can still expect to experience a decrease in the fuel efficiency and an increase in engine emissions of the vehicle in question.
What repairs can fix the P3486 code?
When repairing and clearing a P3486 trouble code, mechanics should perform the following:
- Repair any engine oil leaks.
- Replace any wiring, connectors, or components that are faulty or damaged.
- Replace the throttle position sensor if it is bad.
- Replace the cylinder deactivation solenoid if it is faulty.
- Replace the intake control manifold absolute pressure sensor if it tests as bad.
- Replace the mass airflow sensor if needed.
- Replace the lifter in Cylinder 11 if it is not working properly. This requires the removal of the valve cover, including any components that might prohibit the valve covers removal.
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