P0847 Honda Civic – Your Comprehensive Guide To Diagnosing And Fixing

There’s nothing quite like the sinking feeling when your Honda Civic’s “Check Engine” light decides to make an unexpected appearance. It can feel like your trusty ride is suddenly speaking a foreign language. If your scanner is showing a p0847 Honda Civic code, you’re not alone, and you’ve come to the right place. This specific code points to a problem with your transmission fluid pressure sensor, a vital component for smooth shifting and overall transmission health.

At FatBoysOffroad, we understand the frustration of diagnostic codes and the desire to tackle problems yourself. We promise to demystify the P0847 code, providing you with expert, actionable insights to diagnose and potentially fix this issue. By the end of this guide, you’ll have a clear understanding of what P0847 means, how to approach its diagnosis, and the steps to take to get your Civic shifting smoothly again. Let’s dive in and empower you to become your own best mechanic!

Understanding the P0847 Honda Civic Code: What It Means for Your Ride

The P0847 Honda Civic diagnostic trouble code (DTC) specifically refers to an issue with the “Transmission Fluid Pressure Sensor/Switch “B” Circuit Low”. In simpler terms, your Civic’s powertrain control module (PCM) or transmission control module (TCM) isn’t seeing the expected electrical signal from a particular transmission fluid pressure switch.

Your Honda Civic’s automatic transmission relies on fluid pressure to engage different gears. These pressure switches monitor that pressure, sending signals back to the computer. If the signal from “Sensor B” (often associated with 3rd or 4th gear pressure, depending on your Civic’s specific transmission) is consistently low or absent, the computer flags it with P0847.

Ignoring this code can lead to more severe transmission damage down the road. It’s not just a light on the dash; it’s your car telling you something needs attention.

Common Symptoms of P0847

While the check engine light is the most obvious sign, you might notice other symptoms accompanying a p0847 Honda Civic code:

Check Engine Light: Illuminated on your dashboard.
“D” Light Flashing: The “D” (Drive) indicator on your instrument cluster might flash, signifying a transmission fault.
Harsh or Delayed Shifts: Your transmission might shift roughly, hesitate between gears, or feel “clunky.”
Transmission Stuck in “Limp Mode”: The transmission might revert to a default gear (often 3rd) to prevent further damage, limiting speed and acceleration.
Reduced Fuel Economy: Inefficient shifting can lead to your engine working harder.

These symptoms indicate that your transmission isn’t operating as it should, and addressing the P0847 code promptly is crucial for your Civic’s longevity.

Common Problems with P0847 Honda Civic: Pinpointing the Culprit

When you encounter a p0847 Honda Civic code, several factors can be at play. Understanding the most common causes will help you narrow down your diagnostic efforts and tackle the problem effectively.

Faulty Transmission Fluid Pressure Switch (The Usual Suspect)

This is by far the most frequent cause. The pressure switches are small, relatively inexpensive components that can wear out over time. They are exposed to transmission fluid and temperature fluctuations, which can degrade their internal electrical contacts.

Internal failure of the switch.
Contamination from dirty transmission fluid.

Replacing the specific pressure switch related to “Sensor B” often resolves the issue. This is a primary focus for any p0847 Honda Civic guide.

Low or Dirty Transmission Fluid

Your transmission relies on clean, correctly leveled fluid for proper operation. If the fluid is too low, the pressure switches might not be able to read pressure accurately. If the fluid is old and dirty, it can clog passages, affect switch operation, and even cause internal damage.

Low fluid levels due to leaks.
Degraded fluid that has lost its lubricating and hydraulic properties.

Checking your transmission fluid is one of the first and easiest steps in troubleshooting.

Wiring Issues: A Common Electrical Headache

The electrical circuit for the pressure sensor includes wiring and connectors. Damage to these can prevent the signal from reaching the PCM/TCM.

Chafed or Damaged Wires: Wires can rub against other components, causing insulation to wear away and leading to shorts or open circuits.
Corroded Connectors: Moisture and debris can get into electrical connectors, causing corrosion and poor electrical contact.
Loose Connections: Vibrations can sometimes loosen a connector, leading to intermittent or complete signal loss.

A thorough visual inspection and continuity test are essential here.

Transmission Control Module (TCM) or Powertrain Control Module (PCM) Issues

While less common, a faulty TCM or PCM could also be the root cause. These modules interpret the signals from the sensors and control the transmission’s operation. If the module itself is failing, it might misinterpret sensor data or fail to send the correct commands.

Internal circuit board failure.
Software glitches (rare, but possible after a flash).

This is usually diagnosed after ruling out all other possibilities, as it’s a more complex and expensive fix.

How to P0847 Honda Civic: A Step-by-Step Diagnostic Guide

Tackling a p0847 Honda Civic code doesn’t have to be intimidating. With a systematic approach and the right tools, you can often diagnose the problem yourself. Always prioritize safety first: ensure your car is on a level surface, the parking brake is engaged, and the engine is off and cool before working on it.

Initial Checks: Fluid Level and Condition

Before you even think about tools, start with the basics. This is a crucial part of any p0847 Honda Civic care guide.

Locate the Transmission Dipstick: On most Honda Civics, this is a yellow or red handle, often labeled “ATF.”
Check Fluid Level: With the engine at operating temperature (after a short drive) and the car parked on a level surface, pull the dipstick, wipe it clean, reinsert it fully, then pull it out again. The fluid level should be between the “MIN” and “MAX” marks. Consult your owner’s manual for the exact procedure for your model year, as some Hondas require checking in Park, others in Neutral.
Inspect Fluid Condition: Look at the color and smell. Healthy Honda DW-1 ATF is reddish-pink and has a slightly sweet smell. If it’s dark brown or black, smells burnt, or has metallic particles, it’s a sign of significant wear or internal transmission problems.
Top Off or Change Fluid: If the fluid is low, top it off with genuine Honda DW-1 Automatic Transmission Fluid. If it’s dirty or burnt, a fluid change is recommended.

Pro Tip: Never use generic ATF. Honda transmissions are very particular about their fluid type. Using the wrong fluid can cause serious damage.

Inspecting the Transmission Fluid Pressure Switch (Sensor B)

Once you’ve confirmed the fluid is good, your next step is to examine the pressure switch itself. Honda Civics typically have multiple pressure switches, and identifying “Sensor B” is key. For many Civics, “Sensor B” corresponds to the 3rd or 4th gear pressure switch. Consult a service manual for your specific year and model for exact locations.

Locate the Switches: These are usually threaded into the transmission case, often visible from under the hood or under the car. They have a small electrical connector.
Disconnect the Battery: Always disconnect the negative battery terminal before working on electrical components.
Visually Inspect: Look for any obvious physical damage to the switch or its connector. Check for corrosion, bent pins, or signs of rodent damage to the wiring.
Test the Switch (Optional, but Recommended):
- Disconnect the electrical connector from the switch.
- Using a multimeter set to resistance (ohms), probe the two terminals on the switch.
- A good switch should show infinite resistance (open circuit) when not pressurized and a specific low resistance value when activated (e.g., by applying light air pressure if you can safely do so, though this is often difficult without specialized tools). A faulty switch might show a continuous open circuit or short circuit regardless of pressure. Refer to your service manual for the exact resistance specifications for your specific switch.
Inspect the Connector and Wiring: Carefully examine the wiring harness leading to the switch. Look for frayed wires, cracked insulation, or signs of heat damage.

Tools You’ll Need: Multimeter, basic wrench set (for switch removal), flashlight.

Wiring Harness Inspection and Testing

If the fluid and switch seem fine, the wiring harness is the next logical step. This is where how to p0847 Honda Civic gets a bit more involved.

Trace the Wires: Follow the wires from the pressure switch connector back towards the main harness. Look for any pinch points, areas where the wires might rub, or signs of rodent damage.
Check for Continuity:
- With the battery still disconnected, disconnect the connector at the pressure switch and, if possible, at the PCM/TCM (consult a wiring diagram for pinouts).
- Using your multimeter set to continuity mode, probe each wire from one end to the other. You should hear a beep or see a reading close to zero ohms.
- If you get no continuity, there’s a break in the wire.
Check for Shorts to Ground/Power:
- With the switch disconnected, test each wire from the connector to a known good ground on the chassis. You should see infinite resistance. If you get a low resistance, the wire is shorted to ground.
- Similarly, test each wire to a positive battery terminal (if applicable, ensuring no power is flowing).

Repair any damaged wiring using proper soldering and heat-shrink tubing for a durable fix. Avoid electrical tape alone, as it won’t last in the engine bay environment.

DIY Fixes and Best Practices for P0847 Honda Civic Care

Once you’ve diagnosed the likely cause, it’s time to put your DIY skills to the test. These p0847 Honda Civic tips will guide you through common repairs.

Replacing the Transmission Fluid Pressure Switch

If your diagnosis points to a faulty switch, replacement is straightforward for most DIYers.

Gather Your Tools and Parts: You’ll need the new OEM Honda pressure switch (part numbers vary by year/model, so verify before purchasing), a wrench or socket to remove the old switch, a drain pan, and fresh Honda DW-1 ATF if you plan to top off.
Safety First: Park on a level surface, engage the parking brake, and allow the engine to cool. You might need to raise the front of the car with a jack and secure it with jack stands for easier access.
Locate and Drain: Place your drain pan under the switch. Unscrew the old pressure switch. A small amount of transmission fluid will drain out. Be prepared for this.
Install the New Switch: Apply a small amount of new transmission fluid to the O-ring of the new switch. Thread it in by hand to avoid cross-threading, then tighten it to the manufacturer’s torque specifications (check your service manual!).
Reconnect and Refill: Reconnect the electrical connector to the new switch. Check your transmission fluid level and top off as needed.
Clear the Code: Use your OBD-II scanner to clear the P0847 code.
Test Drive: Take your Civic for a test drive, paying attention to shifting behavior. The code should not return.

Pro Tip: Always use genuine Honda parts for critical transmission components. Aftermarket switches can sometimes cause intermittent issues or premature failure, which isn’t very sustainable p0847 Honda Civic practice.

Transmission Fluid Flush and Filter Replacement (If Applicable)

If your transmission fluid was dirty or burnt, a fluid change is highly recommended. Some Honda Civics also have an external transmission filter that can be replaced.

Drain and Refill: Perform a standard drain and refill of the transmission fluid. For best results, multiple drain and refills (a “3x drain and fill”) might be needed to replace most of the old fluid.
Replace Filter (If Accessible): If your Civic has an accessible external filter, replace it during the fluid change. Not all Civics have easily replaceable external filters.
Benefits of Addressing P0847: Beyond just clearing the code, fresh fluid ensures proper lubrication, cooling, and hydraulic function, extending the life of your transmission and restoring smooth shifts. This is a key part of long-term p0847 Honda Civic best practices.

Note: A full transmission “flush” using a machine is often debated. Many mechanics prefer multiple drain and fills for Honda transmissions to avoid dislodging debris that could cause new problems.

Sustainable P0847 Honda Civic Solutions: Long-Term Reliability

Beyond the immediate fix, thinking about the longevity of your Honda Civic’s transmission is crucial. Adopting sustainable p0847 Honda Civic solutions means focusing on preventative maintenance and smart choices.

Regular Transmission Fluid Maintenance

The single most impactful action you can take for your transmission is regular fluid maintenance. Follow Honda’s recommended service intervals for transmission fluid changes, typically every 30,000 to 60,000 miles, depending on your driving conditions. If you do a lot of stop-and-go driving, towing, or live in extreme climates, more frequent changes are beneficial.

Check Fluid Regularly: Make checking your ATF a part of your routine oil change checks.
Use Only Honda DW-1 Fluid: We can’t stress this enough. It’s engineered specifically for Honda transmissions.
Proper Disposal: Ensure old transmission fluid is disposed of at an authorized recycling center. This is an easy way to be eco-friendly p0847 Honda Civic conscious.

Clean, healthy fluid prevents premature wear on all internal transmission components, including pressure switches.

Quality Parts and Proper Installation

When replacing components, invest in quality. Genuine Honda parts, while sometimes more expensive, offer peace of mind regarding fitment, durability, and compatibility.

OEM vs. Aftermarket: For critical components like transmission sensors, OEM is often the safest bet.
Torque Specifications: Always tighten fasteners to their specified torque. Overtightening can strip threads; undertightening can lead to leaks or loose components.

Proper installation ensures the repair lasts and prevents new issues from arising.

Mindful Driving Habits

Your driving style also plays a role in transmission longevity.

Avoid Hard Acceleration/Deceleration: Smooth inputs are easier on the transmission.
Don’t “Power Brake”: Holding the brake and accelerator simultaneously puts immense strain on the transmission.
Warm Up: Allow your car a minute or two to warm up, especially in cold weather, allowing the transmission fluid to circulate properly before heavy driving.

These habits contribute to the overall health of your transmission, reducing the likelihood of codes like P0847 appearing.

When to Call a Pro: Safety First!

While many P0847 issues are DIY-friendly, there are times when calling a licensed professional is the smartest and safest option. Knowing your limits is part of being a responsible DIYer.

Complex Electrical Diagnosis: If you’ve checked the fluid and replaced the switch, but the code persists, the issue might be deeper in the wiring harness or even the PCM/TCM. These require advanced diagnostic tools and expertise.
Internal Transmission Concerns: If your fluid is burnt, has metallic particles, or you experience severe shifting problems, it could indicate internal transmission damage that requires a specialist.
Lack of Confidence or Tools: If you’re uncomfortable working under the car, don’t have the right tools (like a reliable multimeter or service manual), or simply feel out of your depth, a professional can provide peace of mind.
Persistent Code: If the P0847 code returns shortly after your DIY fix, it suggests an underlying issue that needs further investigation by an expert.

A reputable transmission shop or Honda dealership will have the specialized diagnostic equipment and experience to accurately pinpoint and repair complex transmission problems, ensuring your safety and the long-term health of your vehicle.

Frequently Asked Questions About P0847 Honda Civic

Can I drive with a P0847 code?

While you might be able to drive your Civic with a P0847 code, it’s generally not recommended for long periods. The code indicates a transmission issue that can lead to harsh shifting, limp mode, and potentially more severe, expensive damage to your transmission if left unaddressed. Get it checked out as soon as possible.

How much does it cost to fix P0847?

The cost can vary significantly. If it’s just a faulty transmission fluid pressure switch, the part itself might be $30-$100, and it’s a relatively easy DIY fix. If you take it to a shop, labor could add another $100-$200. If the issue is more complex, like wiring damage or an internal transmission problem, costs could climb much higher, potentially into hundreds or even thousands for major transmission repairs.

What’s the difference between pressure sensor A and B?

Honda transmissions use multiple pressure sensors/switches, each monitoring fluid pressure in different circuits or for different gear engagement points. Sensor “A” might refer to one circuit (e.g., 2nd clutch pressure), while Sensor “B” refers to another (e.g., 3rd or 4th clutch pressure). The exact designation varies by Honda model and transmission type, so always consult your specific service manual.

Will a transmission fluid change fix P0847?

A transmission fluid change can sometimes resolve a P0847 code, especially if the fluid was low or extremely dirty, impacting the pressure switch’s ability to function. However, if the switch itself is faulty or there’s an electrical issue, a fluid change alone won’t fix it. It’s a good first step in diagnosis, though.

Is P0847 common in Honda Civics?

Yes, transmission fluid pressure switch failures, leading to codes like P0847, are fairly common issues across many Honda models, including the Civic, as these switches are wear items. It’s one of the more frequently encountered transmission-related codes for Honda owners.

You’ve got this! Addressing a p0847 Honda Civic code doesn’t have to be a nightmare. With the right information, a methodical approach, and a commitment to safety, you can often diagnose and resolve this issue yourself. Remember, proactive maintenance, like regular transmission fluid checks and changes, is your best defense against future codes and ensures your Civic remains a reliable daily driver or a capable off-road companion.

Keep those wheels turning, stay safe, and enjoy the satisfaction of a job well done!

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Thomas Corle

Founder & Automobile expert at FatBoysOffroad

Automobile expert and off-road enthusiast, sharing in-depth knowledge of vehicles, gear, and adventures. Helping readers make smart decisions and enjoy the thrill of off-roading safely and confidently.