How severe is this DTC?
Besides the fact that cylinder deactivation issues can reduce fuel efficiency, possible causes can lead to catastrophic engine failure. P3400 should be rectified as soon as possible and classified as severe.
What are some of the symptoms of the code?
Symptoms of a P3400 trouble code may include:
- Reduced fuel efficiency
- Reduced engine performance
- Other cylinder deactivation codes
- Engine misfire codes
What are some common causes of the code?
Causes of this code may include:
- Low engine oil level or pressure
- Faulty variable valve timing control solenoid(s)
- Open or shorted cylinder deactivation circuit(s)
- PCM programming error or faulty PCM
What are the troubleshooting steps for P3400?
Note: There are known Technical Service Bulletins (TSBs) for certain Honda and Acura vehicles related to this code. These include Honda TSB 11-033, Honda TSB 13-031, and Honda TSB 13-055.
Components essential to the operation of the cylinder deactivation system frequently require engine oil pressure assistance. For this reason, diagnosing cylinder deactivation codes should begin by ensuring the engine is filled to the appropriate level with the correct oil and that engine oil pressure meets specifications. If actual engine oil pressure is in doubt, a manual oil pressure test is necessary.
To achieve an accurate diagnosis of a P3400 code, a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a vehicle information source will be required. If engine oil pressure is in question, a manual pressure gauge will also be needed.
A reliable vehicle information source can produce applicable Technical Service Bulletins (TSBs) that could assist in your diagnosis. It should also provide diagnostic flowcharts, wiring diagrams, connector face views, connector pinout diagrams, and component testing procedures/specifications. You will need this information to reach a correct diagnosis.
Always disconnect controllers before testing system circuits with the DVOM. Failure to do so may damage the controller.
Once you have verified that engine oil pressure meets specifications and performed a visual inspection of associated connectors and wiring, connect the scanner to the vehicle’s diagnostic port. Retrieve all stored codes and associated freeze frame data. Writing down this information (for later reference) may prove useful. Clear the codes and test-drive the vehicle until the PCM enters readiness mode or the code resets.
If the PCM enters readiness mode, you can assume you are dealing with an intermittent code. The conditions that caused it may need to worsen before you can achieve a successful diagnosis. If the code resets, look up the appropriate diagnostic flowchart in the vehicle information source and follow it to conclusion.
Use the DVOM to test the various variable valve timing solenoids. Solenoids that do not meet manufacturer specifications should be considered faulty.
Low engine oil level is the primary contributor to cylinder deactivation system codes