OBD-II trouble code
P3400: Cylinder Deactivation System – Bank 1
Application matters: Stellantis 18-002-25 names Bank 1 for its listed 2023 Ram 1500 5.7L eTorque application. Honda’s 2013 Pilot bulletin has separate vehicle and recorded cold-start conditions; its 2021 message uses the P3400 VPS stuck-off Bank 1 name for specified 2017 applications.
A Bank 1 cylinder-deactivation system report needs the actual engine procedure. The same code appears in a qualified Honda cold-start oil-pressure case and a separate Ram software case; it does not select a pressure switch or engine repair.
Quick facts
- System
- Powertrain
- Category
- Cylinder Deactivation
- Severity
- Medium severity
- Driving guidance
- Depends on symptoms and vehicle guidance
- Repair cost range
- Get a vehicle-specific estimate after diagnosis.
- DIY difficulty
- Shop recommended
A code alone cannot establish whether driving is safe. Stop safely for a red brake or oil-pressure warning, overheating, severe misfire, stalling, or impaired braking or steering, and follow the owner's manual. Restraints faults can reduce crash protection even when the vehicle runs normally.
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What does P3400 mean?
P3400 identifies the cylinder-deactivation system for Bank 1 in the cited Stellantis descriptor. Cylinder-deactivation reports must be interpreted for the installed engine. The bank number does not establish a universal left, right, front or rear position or a particular group of cylinders to repair.
Honda provides useful application-specific wording. Its November 2021 message calls P3400 “Valve Pause System (VPS) Stuck Off Bank 1” on specified 2017 Odyssey, Pilot and Ridgeline vehicles. That name helps interpret those records; the dated dealership message is not a repair instruction for every Honda or another make.
Honda bulletin 13-055 describes a different, tightly qualified 2013 Pilot cold-start problem. Excessive oil pressure at the VCM spool valve can cause uncommanded cylinder cutout, with misfire and P3400 or P3497 reports. The bulletin requires the listed vehicle qualification and recorded oil-pressure/temperature conditions. Its matched repair concerns an oil-pressure relief-valve spring, rather than automatically replacing the switch named in its shorthand description.
Stellantis bulletin 18-002-25, dated January 25, 2025, supplies a separate PCM software case for its listed 2023 Ram 1500 5.7L Hemi MDS VVT eTorque configuration. The MIL and listed faults must match; related systems and other symptoms or codes are assessed before its programming procedure. Rough idle or misfire during warm-up may occur. This does not transfer Honda’s spring repair to a Ram or establish software as every P3400 cause.
Save the complete scan, status, available event data and actual warnings before clearing anything. Tell the repairer about cold-start roughness, misfire or recent service that already happened. Do not arrange repeated cold starts, raise engine speed, jump a switch or connect an oil-pressure gauge to reproduce the fault. Pressure testing, engine access and programming belong with qualified service using the correct procedure.
A normal idle later does not settle what happened during the event. Follow vehicle instructions and obtain assistance for severe misfire, a flashing warning, an oil-pressure warning or unsafe operation. Ask for an itemized diagnosis and quote explaining which recorded findings support the repair, what parts or programming are justified and how the result will be verified.
Possible causes
- Excessive cold-start oil pressure in the precisely matched Honda 13-055 case
- PCM software in the qualified Stellantis 18-002-25 application
- Another confirmed deactivation or control condition established by the engine-specific diagnosis
Symptoms
- A MIL and stored P3400 with application-specific wording or companion faults
- Cold-start misfire in the matched Honda case, or warm-up roughness in the matched Ram case
- Warnings or running problems that require assessment on their own merits
Diagnostic steps
Save the full scan report, code status, and available freeze-frame data before clearing anything. Confirm the reporting module, any failure-type suffix, and the procedure for the exact vehicle. The steps below are an overview; use manufacturer specifications and safety procedures for testing.
- 1.Preserve the full scan, status, available freeze-frame information and symptoms before clearing.
- 2.Have the engine’s Bank 1 meaning and actual deactivation procedure identified, including any manufacturer alias.
- 3.For the Honda example, have the vehicle and recorded cold-start conditions checked against 13-055; do not infer low oil or a failed switch from its shorthand.
- 4.For the Ram example, have the exact configuration, listed complaint and other systems assessed before any qualified PCM update.
- 5.Leave connected pressure tests, engine disassembly, switch tests and programming to qualified service; request the demonstrated repair and confirmation in an itemized estimate.
Repair cost
Get a vehicle-specific estimate after diagnosis.
A trouble code alone does not price the repair. Ask the shop to identify the confirmed fault and itemize diagnosis, parts, labor, programming or calibration, and taxes.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with vehicle-specific fault diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
Related repairs
These links are planning examples; the code does not confirm that any listed part has failed.
DIY vs shop
A qualified shop is recommended because this can involve manufacturer-grade tooling, training, or certification that most home setups do not have. Ask the technician what testing confirmed the repair.