P3458 code definition
The P3458 code is stored when the measured values for cylinder deactivation mode are not within the range of manufacturer-specified values.
What the P3458 code means
In order to provide good fuel economy, vehicles are designed to deactivate certain cylinders during idling, starting, or other situations. Deactivation occurs when the intake and exhaust valves are prevented from opening by locking pins. During this deactivation, the MAF sensor, the MAP sensor, and the TP sensor are all measuring emissions values and voltage values related to the operation of cylinders. If the system has registered a command to deactivate, but the measured values don’t match what the system knows it should see in this situation, the system registers a fault, and sends the P3458 code to the PCM.
What causes the P3458 code?
There are a variety of issues that could cause the P3458 code to be stored within the PCM. These may include:
- Poor electrical connection within the cylinder deactivation solenoid circuit
- An open or shorted cylinder deactivation solenoid harness
- Low oil pressure
- Restricted oil flow
- A mechanical condition within the engine
What are the symptoms of the P3458 code?
Typically, the only symptom that will be experienced when the P3458 code is stored in the PCM is the illumination of the Check Engine Light. Some vehicle owners may register a decrease in fuel economy.
How does a mechanic diagnose the P3458 code?
In order to diagnose the P3458 code, a technician will first scan with the OBD-II scanner and collect the data from the PCM. They should then check all of the solenoid wiring components and connectors, looking for any corroded, loose, shorted, or open components and repairing as necessary. When electrical issues have been eliminated, the technician will continue to go through other possible repairs for the P3458 code.
Common mistakes when diagnosing the P3458 code
The most common mistake when diagnosing a code like the P3458 is failure to clear the code after each possible repair, and performing a retest. The easiest way to repair an issue is often to duplicate the failure. If the technician remembers to perform this system clear after each possible repair, it will be much easier to pinpoint the issue.
How serious is the P3458 code?
The P3458 is a very serious issue that needs to be repaired as soon as it is detected. This code indicates that there may be a major malfunction in the vehicle’s ability to deactivate cylinders, which could cause a misfire or total engine failure.
What repairs can fix the P3458 code?
In order to repair the issue causing the P3458 code to be stored in the PCM, a technician will likely begin by checking the electrical components during their diagnostics. If these repairs do not clear the code, other possible repairs include:
- Replacing or repairing the faulty solenoid
- Replacing or repairing the solenoid harness
- Repairing any issues causing low or restricted oil pressure
- Replacing faulty MAF, MAP, or TP sensors
If the issue is related to an electrical problem in the engine, these repairs could take longer to diagnose and address. In extreme cases, the ECM may need to be replaced.
Additional comments for consideration regarding the P3458 code
The P3458 code is related to the operation of cylinder 8, which may be accompanied by fault codes for the operation of other cylinders, particularly if the issue is related to the common power source that the solenoid harnesses for each use. If there are multiple fault codes related to the operation of cylinders, a pinpoint test to discover the exact area of fault may be required.
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