Question

How to fix P1259 code 

The P1259 error code, hinting at a possible V-tech system malfunction can be fixed easily. One of the first steps to fixing this code is to check the engine oil level and condition- because insufficient oil or contaminated oil is one of the most common causes of this code.

Here are the other reasons that could be causing a P1259 code: 

• The VTEC solenoid is defective.  
• A broken VTEC oil pressure switch.  
• Damage to VTEC solenoid cables or connectors could result in an open or short circuit.  
• The engine oil level or pressure may be lower than what’s required.  
• Presence of dirty, degraded, or unsuitable engine oil.  
• Failure of PCM. Since this is an uncommon cause, you need to check the fault somewhere else before replacing any control module.

It’s relatively easy to find the primary cause of this code. If you still have a hard time finding the reason behind the code, you could get a proper diagnosis by seeking professional help. They will do the following to diagnose it: 

• On Bank 1, perform a VTEC Cylinder Balance test to ensure that all cylinders generate power.  
• Check for 12 volts at the solenoid connector while turning on the ignition switch to confirm it is working properly (RUN).  
• Check for any issues with the engine’s oil pressure. Perform additional diagnostics on the vehicle if there is no or low oil pressure.  
• On V-type engines, inspect and clean up all electrical connections in the circuit. If everything else checks out fine, check if there is good power production from each bank.  
• Check for any hissing noises and look for shorts in VTEC Control Solenoid Valve A and B circuits. Make sure the ignition switch is in the ON (RUN) position while doing this.  
• Even after resolving problems with the oil pressure or electrical issues, if the problem persists, then it’s best to replace the VTEC solenoid.  

Once diagnosed, you can go ahead and rectify the problem. Common fixes include:

• Checking whether the oil is due for servicing. If the oil is contaminated or the filter is clogged, replace both. Once it’s completed, clear the code before checking the engine. Don’t forget to check the oil pressure.  
• Another possible reason for the code could be a problem with the VTEC oil pressure switch. Try to have it repaired, but if you are replacing it, make sure to use an authentic oil pressure switch that suits your Honda/Acura.  
• Inspect the VTEC system for any physical damage. Look through the solenoid, electrical circuit wires, connectors, and other components thoroughly. If you come across any damage, make sure to repair or replace it.