P1399 Honda – Random Cylinder Misfire Detected

Introduction To P1399 Honda OBD2 

P1399 is a manufacturer-specific code, not a generic one. You will find it in any Honda vehicles – including Honda Accord, Honda CRV, Honda Odyssey, Honda Civic, etc. It shows up whenever there is a random misfire in the engine.

Just locate the vehicle’s OBD2 system to begin the diagnostic process, and you will readily detect this error code.

There are possible steps to follow to correct this issue. Check the provided step-by-step guide in this post for a better understanding.

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Code P1399 Honda Definition And Meaning (Technical Description)

P1399 Honda Definition:

Random Cylinder Misfire Detected

Meaning of P1399 on Honda cars

P1399 signifies a random cylinder misfire in your Honda. You are likely to see it if your car’s crankshaft fluctuates in speed. This OBD2 code can easily be picked up by a Crankshaft Positioning (CKP) sensor. The CKP sensor then passes the error to the Engine Control Module (ECM) from where the issue is confirmed.

Symptoms Of P1399 On Honda

A vehicle experiencing engine misfire most often gives you one or more warning signs. Some of these signs could be visible; others are only felt. As a result, you need to be keen enough to spot all these telltale signs before the issue worsens. The symptoms of P1399 are:

  • Check Engine light turns on (This is also known as a malfunction indicator lamp)
  • A hard start experience
  • Engine hesitation issues
  • Lack or loss of engine power

Causes Of P1399 On Honda

There are two leading causes of the P1399 Honda error code. These include a:

  • Valve clearance not in the normal range
  • Clogged exhaust gas recirculation (EGR) Passages

How Serious Is The P1399 Code For Your Honda?

Under any circumstance, never try to continue driving. This advice is especially true if you still don’t know the cause or extent of the damage. Otherwise, the issue might be worsened, making it more costly to repair. Correct the problem as soon as you spot the first symptom. It will save you from all unwanted stress and disappointment.

How To Diagnose And Fix The Code P1399 On Your Honda?

Tools Needed 

You need two crucial tools for the process. First is an OBD2 scanner, which will help you know if you are experiencing P1399. Second is a multimeter to test the vehicle’s electrical components.

Procedure To Diagnose And Fix the Code

Step 1: Prepare Your Tools

Gather your OBD2 scanner and multimeter to ensure that they work well. 

Step 2: Retrieve The Error Codes: 

Use your OBD2 scanner to retrieve the codes causing your engine to misfire. Most often, you will find P1399 alongside codes like P0301, P0302, P0303, and P0300. Don’t be surprised since all these are misfiring codes. Always try solving these other codes to see if the situation becomes any different.   

Step 3: Scan Electrical Components

Cylinder misfire is, at times, attributed to computer or wiring problems. Use your multimeter to see if the vehicle’s electrical components are in a good state. Correct any fault you find. Otherwise, move to the next step.

Step 4: Check Ignition Coils: 

Test your ignition coils to see if one or more are causing the misfire. Do this by unplugging one at a time while the engine is left on idle. Keenly observe the sound produced by the engine when you unplug each. A faulty coil won’t make any changes in engine sound when unplugged. Pull it out to see if it is cracked or damaged in any way. You’ll have to replace or adjust all faulty coils. 

Step 5: Check Oxygen Sensors: 

A bad oxygen sensor always throws off the fuel-combustion system. It causes an imbalance in fuel to air ratio. It also allows too much fuel into the engine, reducing the vehicle’s gas mileage, which causes the engine to misfire, one of the probable causes of P1399 in Honda vehicles. Check to see if it is in a good state. You must check and correct any faults found. 

Step 6: Check Your Valve Clearance: 

A blocked or clogged valve clearance can cause the error. At times, the valves become too tight or too loose, making them close and open irregularly. Make the necessary adjustments to ensure enough space for valve expansion when the valves heat up. Tighten or loosen then a bit. 

Step 7: Check Your Exhaust Gas Recirculation: 

Is your EGR clogged? If yes, then this could be the cause or one of the causes of the P1399 error. Unclog it for a smooth flow of exhaust gasses within the system.

If these solutions fail, then you will have to go deeper into your engine. You might have to look at components like the vehicle’s piston rings and valves. Seek professional advice if the issue is unresolved. It might be more in-depth and more technical than you think. Consider hiring a qualified automotive technician in such situations to make the work more comfortable since they have the right tools and expertise for such challenging tasks.

Tips To Avoid P1399 In The Future 

The best solution is to service the vehicle frequently. You can do this on your own or hire a professional technician to ensure that the engine is always operating at optimum levels. Form a habit of continuously checking and replacing faulty parts such as ignition coils and spark plugs. Keep checking your clearance valves to ensure that they are not too tight or loose. Adjust each of them as is required. You should also ensure that your EGR passage remains unclogged. Kindly note that you must adjust the valves every 50,000 miles. All in all, be keen while driving your vehicle. Try not to dismiss warning signs such as when the Check Engine light turns on.

Read More: 8 Best OBD2 Scanners for Honda 2024 [Comparison & Review]