Technical Description of OBD-II Trouble Code
The circuit controlling the exhaust valve of cylinder 7 is experiencing high voltage.
What does that mean?
This is a generic diagnostic trouble code (DTC) for the powertrain and is applicable to many OBD-II vehicles manufactured from 1996 onwards. This includes vehicles from Dodge, Peugeot, Jeep, Chevrolet, Chrysler, and others. While the code is generic, the specific repair steps may vary depending on the year, make, model, and engine configuration of the vehicle.
OBD-II trouble code P3456 and related codes P3453, P3454, and P3455 are associated with the circuit controlling the exhaust valve of cylinder 7.
The purpose of the circuit controlling the exhaust valve of cylinder 7 is to deactivate the exhaust valve in order to enable cylinder deactivation, such as the V4 mode of a V8 engine. This improves fuel economy during light load operation at idle or on the highway. The Engine Control Module (ECM) controls the activation and deactivation of four or eight cylinders in the engine. This is achieved through variable valve timing solenoids that turn the exhaust valves on and off as needed. This code specifically relates to cylinder 7, while the other three cylinders involved in this process are determined by the engine configuration and firing order. The variable valve timing solenoid for cylinder 7 is located near the exhaust manifold in the vicinity of that cylinder, based on the specific configuration and vehicle.
When the ECM detects voltage or resistance that is higher than the normal expected range in the circuit controlling the exhaust valve of cylinder 7, it sets code P3456 and may illuminate the check engine light, service engine soon light, or both. In some cases, the ECM may disable the injector for cylinder 7 until the issue is resolved and the code is cleared, resulting in a noticeable engine misfire.
Cylinder Deactivation Solenoids:
What is the severity of this DTC?
The severity of this code can vary greatly from moderate to severe, depending on the specific symptoms of the malfunction. A misfire should be addressed immediately as it can cause permanent damage to internal engine components.
What are some of the symptoms of the code?
Symptoms of a P3456 trouble code may include:
What are some of the common causes of the code?
Causes for this P3456 code may include:
What are some P3456 troubleshooting steps?
The first step in troubleshooting any malfunction is to research the Technical Service Bulletins (TSBs) specific to the vehicle’s year, model, and engine. This can save time and money as it provides a known fix for a known issue.
The second step is to check the engine oil level and ensure it is at the appropriate level. Then, inspect all components associated with the circuit controlling the exhaust valve of cylinder 7 for any visible physical damage. Depending on the specific vehicle, this circuit may include several components such as the variable valve timing solenoid, switches, fault indicators, and the ECM. Conduct a thorough visual inspection of the wiring associated with these components, looking for any obvious defects such as scraping, rubbing, bare wires, or burn spots. Next, check the connectors and connections for security, corrosion, and damaged pins. Consult the vehicle’s specific technical data to verify the configuration and identify every component involved in the circuit controlling the exhaust valve of cylinder 1.
Advanced Steps
The advanced steps are highly specific to the vehicle and require advanced equipment for accurate execution. These procedures necessitate the use of a digital multimeter and the specific technical references for the vehicle. In this situation, an oil pressure gauge may also aid in the troubleshooting process to confirm the presence of an oil passage restriction.
Voltage Checks
The reference voltage and acceptable ranges may vary depending on the specific vehicle and circuit configuration. The specific technical data will include troubleshooting charts and the appropriate sequence to follow for an accurate diagnosis.
If this process reveals the absence of a power source or ground, continuity testing may be necessary to check the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power removed from the circuit, and normal readings for wiring and connections should show 0 ohms of resistance. Resistance or lack of continuity indicates faulty wiring that is open, shorted, or corroded and must be repaired or replaced.
What are some common repairs for this code?
Common Mistake
We always recommend seeking professional mechanical service to address this issue. However, if that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to be addressed. If you are interested in this option, please upload your ECU file to our portal.
