Low engine oil level or degraded oil preventing proper VTEC oil pressure; Faulty VTEC oil pressure switch on the rear bank; Clogged VTEC solenoid screen or oil passage; Failed VTEC solenoid or wiring issue (open, short, or corrosion); Sticking VTEC rocker arm or spool valve; Engine mechanical wear reducing oil pressure to the VTEC system

DTC codes / Honda codes / P1259

P1259 · HondaVTEC System Malfunction Rear Bank 1

Q: What does code P1259 mean?

VTEC System Malfunction Rear Bank 1. P1259 on Honda vehicles indicates that the powertrain control module has detected a malfunction in the VTEC (Variable Valve Timing and Lift Electronic Control) system for the rear bank of cylinders. The computer monitors oil pressure switches and solenoid circuits and sets this code when the expected change in valve timing does not occur or the electrical circuit is out of range.

P1259 on Honda vehicles indicates that the powertrain control module has detected a malfunction in the VTEC (Variable Valve Timing and Lift Electronic Control) system for the rear bank of cylinders. The computer monitors oil pressure switches and solenoid circuits and sets this code when the expected change in valve timing does not occur or the electrical circuit is out of range.

SystemPowertrain

Code typeHonda specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Reduced engine power or a limp-home mode above a certain RPM
Rough idle or stalling, especially when cold
Poor fuel economy or increased emissions
Audible valve train noise or ticking from the rear bank
Hesitation or stumble during acceleration

Common causes, most likely first

Low engine oil level or degraded oil preventing proper VTEC oil pressure
Faulty VTEC oil pressure switch on the rear bank
Clogged VTEC solenoid screen or oil passage
Failed VTEC solenoid or wiring issue (open, short, or corrosion)
Sticking VTEC rocker arm or spool valve
Engine mechanical wear reducing oil pressure to the VTEC system

How to diagnose and fix it

Check engine oil level and condition; top off or change oil if needed
Inspect the VTEC solenoid connector and wiring for damage or corrosion
Remove and clean the VTEC solenoid screen and oil passages
Test the VTEC oil pressure switch with a multimeter and replace if faulty
Measure oil pressure at the VTEC port to confirm mechanical integrity
Replace the VTEC solenoid assembly if electrically or mechanically failed
Clear the code and perform a road test to verify the repair

Before you replace the VTEC solenoid

A low oil level or severely degraded oil is the most common cause of P1259, so always verify oil condition before condemning any component.
The rear bank VTEC system on V6 Honda engines is often neglected during maintenance, leading to clogged screens that mimic solenoid failure.
A faulty oil pressure switch can set P1259 even when the VTEC mechanism works perfectly, so test the switch before replacing the solenoid.
Wiring harness damage near the rear valve cover can cause intermittent P1259 codes that appear only under certain engine vibrations.
After repairs, the PCM may require a relearn procedure or several drive cycles before the code clears permanently.

Can I keep driving with P1259?

You can usually drive the vehicle with P1259, but avoid aggressive acceleration and high RPMs because the VTEC system may not engage properly, which can lead to reduced performance and potential engine damage over time. Have the fault diagnosed promptly to prevent worsening symptoms.

Tools that help

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Guidance is general and written for Honda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.