How To Fix Honda Engine Error Code P3400

By | January 14, 2023

Honda P3400 Engine OBDII Error Code
If you have a Honda with a P3400 OBDII error code the onbard computer is seeing a problem with the oil pressure.

This includes the Honda Odyssey, Pilot, Stream, Shuttle, Accord, Palisade and more.

What is a Honda P3400 Engine OBDII Error Code?

A Honda with an Error Code P3400 is a “Cylinder Deactivation System Bank 1“.

Some scan tools will also give a “Valve Pause system (VPS) Stuck Off Bank 1”.

This error can be caused by several things but is commonly caused by a bad oil pressure sensor.

Be sure to check the dipstick if the oil level is good, as low oil level will cause this problem.

Possible Causes of a Honda P3400 Engine Error Code

  • Low oil level
  • Old dirty oil
  • Faulty oil pressure sensor
  • Defective cylinder deactivation solenoid
  • An open or short in the cylinder deactivation solenoid harness
  • A bad electrical connection in the cylinder deactivation solenoid circuit
  • Defective mass airflow sensor
  • Defective throttle position sensor
  • Defective intake control manifold absolute pressure sensor
  • Defective lifters
  • Restricted oil passages
  • Low engine oil level
  • No oil on the lifters

The first thing to check is the oil and be sure it is at the proper level and not dirty and grimy, as this can cause oil pressure issues.

A bad oil pressure switch sensor is a common issue with Honda and a P3400 error code.
How To Fix Honda Engine Error Codes P3400 Sensor
While this is a common cause, it is not the only thing that can cause an error code P3400.

Often, the oil pressure switch sensor is replaced first since it is a common problem with Honda’s such as the Odyssey and is a low-cost part.

Bad wiring or ECM could also cause this error code.

How To Fix Honda Engine Error Code P3400 (Replace Oil Sensor)

  1. The sensor is located at the right rear of the engine behind the throttle body.
  2. How To Fix Honda Engine Error Codes P3400 Pic 2

  3. It will have a wire plug harness that will need to come off to remove it.
  4. How To Fix Honda Engine Error Codes P3400

  5. A 24mm Deep Socket will need to be used to remove it.
  6. Once the old sensor is removed, install the new unit making sure it seals good as to not leak oil.
  7. How To Fix Honda Engine Error Codes P3400 Pic 4

Fixing a P3400 trouble code is usually easy enough and falls in the DIY category.

Of course, if in doubt call a professional certified mechanic.

The P3400 code will be given by an OBDII scanner tool after the Honda check engine light comes on.

Other OBDII trouble codes may also be given and also need to be looked up for the cause.

A faulty sensor is the usually cause and is commonly replaced.

The year of a vehicle will make a difference as some will be easier to work on than others.

Have you had an issue with a Honda P3400 code? Let us know your thoughts below.

Bob Thomas
Latest posts by Bob Thomas (see all)

9 thoughts on “How To Fix Honda Engine Error Code P3400

  1. Zachary

    “I changed the the oil pressure switch in my Honda Accord 2011 and the code came back on PO3400 . Going to get a oil change. ” Do I need to change the wiring harness ? I’m at a loss for words. Don’t Know what to do!!!

  2. Pablo P

    So apparently there are two sensors: Rear and Front.

    How do you know which one it is with this code? Is P3400 the Rear and the front have another code?

    1. Pablo P

      Wait, sorry all. So I see Bank 1 on there.

      Is Bank 1 Rear and Bank 2 Front?

  3. Jason

    I had the P3400 on my 2010 Honda Pilot, and looked up what could be the problem. It was like WebMD, the list of possible problems was scary. lol I followed these steps, and the hardest part was finding the new switch after I dropped it into the engine bay. The light didn’t immediately go out, so I came back in the house to see if there was some sort of delay or if I had to reset it. Then I thought maybe I changed the wrong one, ran back out to move the car back to the garage, but when I started it up, the light was out! BOOYAH! Thanks!

  4. 8thgenacccord couple exl

    My car CEL came on and 3 of the cylinders failed in bank 1 my car sounded and felt like crap. So i check it out I had a p3400 code come up and this little sensor fix it everything car is fine back to normal

  5. Manuel

    I had the code 3400 on my 2009 Odyssey. I replaced the oil sensor and checked the oil level (It is good). After 2 weeks, the light came on again. How likely I got a faulty sensor again? What else can it be? (I believe the front sensor gives a different code, should I change it as well?)

    1. Don

      Check the wires as they can cause the same issues and may be loose or have a bad connection.

  6. Igor

    For what it’s worth, a 15/16″ socket (deep well) works identically to the 24mm socket. Practically no difference between 24mm and 15/16″.


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