If you’re seeing a P1739 code on your Honda Accord, you’re probably looking for a clear explanation. This article will explain the P1739 Honda Accord Code Meaning and guide you through the steps to fix it.
That little check engine light can be worrying, but a P1739 is specific and manageable. It points directly to an issue within your car’s automatic transmission system. Let’s break down what it means, why it happens, and what you can do about it.
P1739 Honda Accord Code Meaning
In simple terms, Diagnostic Trouble Code (DTC) P1739 means “Gear Position Malfunction.” This code is specific to Honda and Acura vehicles with automatic transmissions. Your car’s computer, the Powertrain Control Module (PCM), monitors signals from several sensors inside the transmission.
The PCM expects to see a specific pattern of signals from these gear position switches as you shift. When the signals don’t match what the PCM knows is correct for the reported gear, it triggers the P1739 code. It’s the computer’s way of saying, “The signals I’m getting don’t make sense for the gear we’re supposed to be in.”
What Causes the P1739 Code in a Honda Accord?
Several components can be at fault when this code appears. Here are the most common culprits, starting with the most likely:
- Faulty Transmission Range Switch (Neutral Safety Switch): This is the prime suspect. Located on the transmission, it tells the PCM what gear you’ve selected (Park, Reverse, Neutral, Drive, etc.).
- Problems with the Gear Position Switch Assembly: Inside the transmission, this switch cluster provides direct feedback on which gear is physically engaged.
- Damaged or Shorted Wiring: The wires connecting these switches to the PCM can get frayed, corroded, or damaged by heat.
- Poor Electrical Connections: Loose, dirty, or corroded connectors at the switch or PCM can interrupt the signal.
- Low or Degraded Transmission Fluid: While less common, incorrect fluid level or old, burnt fluid can affect hydraulic pressure and sensor operation.
- Internal Transmission Mechanical Issues: In rare cases, a problem like a worn valve body or faulty shift solenoid could cause mismatched signals.
Symptoms You Might Notice
You’ll almost always see the check engine light (MIL) illuminated. But other symptoms often accompany the P1739 code:
- Harsh or erratic shifting
- The transmission may get stuck in a single gear (often 2nd or 3rd gear “limp mode”)
- Inability to shift out of Park
- The gear indicator on the dashboard may show the wrong gear or flash
- Poor fuel economy due to incorrect gear operation
How to Diagnose a P1739 Code
Safety First: Always secure the vehicle on a level surface with the parking brake firmly engaged. Use wheel chocks if needed.
Tools You May Need: A basic OBD-II scanner, a digital multimeter (DMM), vehicle service manual for wiring diagrams, and basic hand tools.
Step 1: Confirm the Code and Check for Others
Use your OBD-II scanner to confirm P1739 is present. Clear the code and take the car for a short test drive to see if it returns immediately. Also, note any other codes (like P0700 or specific solenoid codes), as they provide important clues.
Step 2: Inspect the Transmission Fluid
This is a quick and easy check. With the engine warm and running, and the car on level ground, pull the transmission dipstick.
- Check the fluid level. Is it within the “Hot” marks?
- Check the fluid condition. Is it bright red and translucent, or is it dark brown/black and smell burnt? Low or burnt fluid can cause many issues.
Step 3: Visual Inspection of Wiring and Connectors
Locate the Transmission Range Switch (usually on the side of the transmission case where the shift lever cable attaches). Follow the wiring harness from the switch back.
- Look for obvious damage, chafing, or melted wires.
- Disconnect the electrical connectors (with battery disconnected) and check for corrosion, bent pins, or loose fits.
Step 4: Test the Transmission Range Switch
This is the most common fix. You can test the switch’s resistance with a multimeter. You’ll need to find the correct pinout diagram for your specific Accord year. Generally, you’ll check for continuity (low resistance) between specific pins in each gear position (P, R, N, D, etc.). The resistance should change as you move the shift lever. No change or infinite resistance indicates a bad switch.
Step 5: Consult Professional Help if Needed
If wiring and the range switch check out, the problem may be internal (gear position switch or valve body). Diagnosis at this point often requires specialized knowledge, a scan tool that can read transmission data, and possibly dropping the transmission oil pan. This is when a trusted mechanic becomes very helpful.
How to Fix the P1739 Code
The fix depends entirely on your diagnosis. Here are the common repairs:
1. Replacing the Transmission Range Switch
This is a common DIY repair for many.
- Disconnect the negative battery terminal.
- Unplug the electrical connector from the switch.
- Remove the shift cable linkage from the switch lever.
- Unbolt the switch from the transmission (usually 2-3 bolts).
- Install the new switch. Critical: The switch must be adjusted. Usually, you align a pin or mark on the switch with the lever in Neutral before tightening the bolts. Refer to a manual for your model’s exact procedure.
- Reconnect the linkage and electrical connector.
- Reconnect the battery, clear codes, and test drive.
2. Repairing Damaged Wires
If you found damaged wiring, carefully splice in new wire using solder and heat shrink tubing. Never use twist-on connectors in a vehicle’s engine bay—they vibrate loose and corrode.
3. Addressing Internal Issues
If an internal gear position switch or valve body is faulty, the repair becomes more complex. It often involves removing the transmission oil pan. This is a significant job best left to a transmission specialist, as it requires careful cleaning, precise reassembly, and new fluid and a filter.
Is It Safe to Drive With a P1739 Code?
It is not recommended to drive for long with this code active. The main risks are:
- Stranding: The transmission could enter limp mode, leaving you with only one or two gears, making it unsafe for highway speeds.
- Further Damage: If the cause is related to low fluid or a mechanical issue, continued driving could cause expensive internal damage to the transmission.
- Safety Issue: A faulty range switch might not allow the car to start in Park or Neutral, or it could allow the car to start in gear, causing it to lurch unexpectedly.
If the code appears, get it diagnosed as soon as you reasonably can. Driving a short distance to a mechanic is usually fine, but avoid long trips.
Estimated Repair Costs
Costs vary widely based on the cause and who does the work.
- Transmission Range Switch (Parts): $50 – $150.
- Transmission Range Switch (DIY): Cost of parts only.
- Transmission Range Switch (Shop): $200 – $400 total, as labor is relatively low.
- Internal Switch/Valve Body Repair (Shop): $500 – $1,200+ depending on labor rates and the extent of the work.
This is why proper diagnosis is key—you don’t want to pay for an internal repair when a simple $100 switch was the problem all along.
Preventing Future Issues
Regular maintenance is your best defense.
- Follow Transmission Service Intervals: Change your automatic transmission fluid (ATF) according to your owner’s manual, often every 30,000 to 60,000 miles under severe conditions.
- Regular Inspections: During oil changes, ask the technician to check for any visible leaks or damaged wiring around the transmission.
- Address Electrical Issues Promptly: If you notice other electrical gremlins, get them checked. Corrosion in one connector can spread.
FAQ Section
What does code P1739 mean on a Honda?
It means “Gear Position Malfunction.” The car’s computer detects an illogical signal from the transmission gear sensors.
Can a bad battery cause a P1739 code?
It’s very unlikely to be the direct cause. However, low system voltage can sometimes cause strange electrical issues. If your battery is old or weak, it’s worth checking, but focus on the transmission switches and wiring first.
Is P1739 a serious code?
Yes, it should be taken seriously. While the car may drive for a while, it can lead to being stranded or cause further transmission damage if ignored. The safety risk of incorrect gear indication also makes it serious.
What is the difference between P1739 and P0700?
P0700 is a generic code that means “Transmission Control System Malfunction.” It’s a general alert that there is a problem in the transmission electronic controls. The PCM will usually set a P0700 and a specific code like P1739. P1739 gives you the specific clue.
Will disconnecting the battery clear a P1739 code?
Yes, disconnecting the battery will clear the code from temporary memory. But if the underlying problem is still there, the code will come back, usually within one or two drive cycles. Clearing the code without fixing the cause won’t help.
Can I replace the transmission range switch myself?
Many home mechanics with basic tools can do this job. The most important part is the adjustment during installation. If you’re comfortable with minor mechanical work and can follow a guide for your specific year, it’s a feasible DIY project that saves money.
Final Thoughts
The P1739 code in your Honda Accord is a clear call to action from your car’s computer. It points directly to a communication problem between the transmission’s gear sensors and the PCM. Start with the simple checks: fluid level, then a visual inspection of the Transmission Range Switch and its wiring. More often than not, the fix is replacing that switch.
Ignoring it can lead to more trouble down the road. With a systematic approach, you can diagnose the issue, decide if it’s a job you can handle, or communicate effectively with your mechanic to get your Accord shifting smoothly again. Remember, accurate diagnosis is the first and most important step to a proper, cost-effective repair.