P3440 code definition
The P3440 code reflects a problem with the cylinder deactivation system in bank one.
What the P3440 code means
When you start the ignition or during idling, and when the vehicle is being used to move heavy loads, the engine is going to run on all cylinders. However, if driving conditions are light, the engine will actually deactivate half of the cylinders. In a V8 for example, four of the eight cylinders would be deactivated – effectively making the vehicle a V4.
The vehicle detects driving conditions through the PCM (powertrain control module). It receives data through the MAF (mass airflow) sensor, the TP (throttle position) sensor, and the MAP (intake control manifold absolute pressure) sensor.
Once lighter conditions have been registered, the PCM next initiates the cylinder deactivation solenoids, thus beginning the cylinder deactivation process we described above.
Cylinders to be deactivated will have the oil to their valve lifters restricted which will prevent the exhaust and intake valves from opening. The end result will be those cylinders being deactivated.
As soon as the PCM confirms that the airflow sensor, intake control manifold absolute pressure sensor, and the throttle position sensor are not within the correct range for cylinder shut off mode to activate, the P3440 code is stored.
Without these three sensors being in the correct range, cylinder shut off mode is not possible for the vehicle and, therefore, P3440 code will occur.
What causes the P3440 code?
The P3440 code could be caused for a number of reasons:
- The defective cylinder deactivation solenoid
- The throttle position sensor is defective
- The intake control manifold absolute pressure sensor is defective
- The lifters are defective
- A faulty electrical connection in the cylinder deactivation solenoid harness
- The mass airflow sensor is defective
- Oil passages are restricted
- Oil pressure on the filter is poor
- The engine oil level is too low
- A short or open in the cylinder deactivation solenoid harness
What are the symptoms of the P3440 code?
- You can feel the engine shaking
- The Check Engine Light comes on
How does a mechanic diagnose the P3440 code?
Checking to see if any other diagnostic trouble codes have been stored by the PCM (this is the first thing they’ll do)
Confirming the engine oil levels are acceptable
Clearing the code with the OBD-II scanner
Using the OBD-II scanner to check all of the diagnostic trouble codes that the PCM has stored
Checking cylinder deactivation solenoid seven if solenoid one is working properly
Actuating cylinder deactivation solenoid number seven with a scan tool and, if it works properly, inspecting the oil passages to the lifter
If the oil passages aren’t restricted, replacing the lifters
Otherwise, cleaning any restricted passages – in some cases, the entire engine will need to be taken apart
Common mistakes when diagnosing the P3440 code
Typically, people will forget to check the oil passageways to make sure they’re not being obstructed by sludge or dirt. Restricted passageways inhibit engine oil pressure and prevent lifters and cylinder deactivation solenoids from operating correctly when switching between operating modes.
How serious is the P3440 code?
It’s usually nothing you need to address immediately for the sake of safety, but you wouldn’t want to leave it for an extended period
Until the issue is addressed, the vehicle will be unable to switch to cylinder shut off mode
As a result, engine emissions and a loss of fuel economy will increase
What repairs can fix the P3440 code?
- Cylinder deactivation solenoids one and seven can be replaced
- Clean lifter oil passages
- Clean cylinder deactivation solenoid oil passages
- Replace the engine’s lifters
- Disassemble the entire engine and give it a complete cleaning
Additional comments for consideration regarding the P3440 code
If it becomes necessary to disassemble the entire engine, this is something that should only be undertaken by very experienced technicians.
Need help with a P3440 code?
YourMechanic will actually send a certified mobile mechanic to your home or place of business to assess and repair your vehicle. We’re happy to provide you a quote upfront or schedule an appointment online to learn more about our services. We also invite you to speak with a service advisor by calling us at 1-800-701-6230.