When a car experiences a powertrain-related issue, it is commonly associated with a fault code that can be read via an OBD reader. While most fault codes are engine related, there are several fault codes that can appear due to transmission issues.
On the Honda Accord, more specifically the 6th and 7th gen Accord’s, the P0700 code is common. This code typically means that there is an issue with your automatic transmission. However, a number of things can cause this error code, making it hard to determine what specifically within the transmission system is causing the error.
This guide will cover the symptoms and causes of a P0700 fault code on older model Honda Accords. While this is also applicable to newer versions of the Accord, this problem tends to be most common with late 90’s and early to mid 2000’s Accords with automatic transmissions.
Table of Contents
What is the Accord P0700 Fault Code?
A P0700 fault code will read “Transmission Control System Malfunction”.
This is a generic fault code telling you something is wrong with the transmission. When you get a P0700 code, it also usually has another code with it. There are actually a couple of hundred other transmission fault codes, so diagnosing the issue solely based on a P0700 code can be very difficult.
However, it is not uncommon for your Honda Accord to throw this error code by itself. Fortunately, this is a common issue; therefore, we can narrow down the cause of it to a couple of transmission components.
Using a code reader and scanning all the codes should give you an idea of whether or not you have another code displaying. If you do, then that code will be most helpful in diagnosing the underlying issue.
If you get a P0780 code alongside the P0700 code, this might signal that a new transmission or a rebuild is necessary. A few other codes can indicate a major problem, but the causes tend to be simpler fixes on the Honda Accord.
Symptoms when a P0700 Code Arises
Since this code only arises when there is a transmission problem, you will typically get some symptoms alongside it. The most common are:
- Hard shifting
- Slow or delayed shifting
- Issues downshifting
- Gearbox gets stuck in park or neutral
On the Accord, it is common for only one or two gears to be problematic. However, depending on which gears are affected, you can have issues like being unable to shift into the drive, which obviously makes the car not driveable. Issues will be very noticeable as the shifts will be hard and rough, and you may notice a gear or two being skipped as you upshift or downshift.
Read more: 10 Best transmission code readers
Honda Accord P0700 Causes
As mentioned, this problem is common enough that we can pretty easily pinpoint the issue without digging into a bunch of potential fixes. Before giving the answer away, here are the things that can cause this issue:
- Bad shift solenoid
- TCU failure (transmission control unit)
- Shorted TCU circuit
- Transmission valve body (uncommon)
Out of all the potential causes, a bad shift solenoid is almost always the cause of the problem. While this isn’t to say you can’t have an issue with the trans control module, this is generally less common.
Similarly, the valve body usually doesn’t go bad unless you run your transmission low on fluid. The valve body is essentially a passageway for transporting trans fluid, so if you let your fluid go low, you can significantly damage the valve body.
What is a Shift Solenoid?
The function of shift solenoids is rather technical, but to put it in an easy-to-understand way: they control gear shifts. The solenoids open and close, which controls the flow of transmission fluid to certain gears and helps pressurize them to support the gears shift.
We’ll save the rest of the technical jargon, but their functionality is the reason the transmission has a hard time shifting up or down or out of neutral when they go bad.
The reason the P0700 code really only affects automatic transmissions is that shift solenoids are only on automatic cars. Since they control gear shifting, they aren’t required on manual transmissions since the driver controls gear shifting in a manual.
Older Honda Accord with 5-speed automatic transmission has 3 solenoids. Each is responsible for more than 1 gear which is why you typically have problems with multiple gears when one goes bad.
The newer Accord with 10-speed transmission has 6 shift solenoids. This problem tends to be more common because there are a lot of solenoids, which means the likelihood of one going bad is higher.
Preventing Shift Solenoid Failure
The solenoids pass transmission fluid through them. One of the most common causes of solenoid failure is dirty or old transmission fluid. When gunky fluid passes through the solenoid, it can clog the solenoid and prevent it from functioning properly.
Additionally, the solenoid can fail due to electrical issues, which is also common. However, dirty fluid is the most common culprit.
Performing proper transmission maintenance and frequently flushing the transmission fluid can help prevent the likelihood of transmission solenoid failure.
While a lot of vehicles supposedly come with lifetime transmission fluid, it is a good idea to flush it every 80,000 miles to help prevent any friction within the transmission and keep dirty fluid from causing problems.
Honda Accord Shift Solenoid Replacement
Shift solenoids themselves are pretty inexpensive parts. A solenoid is typically around $25-$50. So you are probably looking at around $100 to $300 in parts to replace all of them, depending on which transmission you have.
However, the solenoids sit within the valve body, so replacing them requires some transmission disassembly. The valve body will have to be pulled from the transmission to access the solenoids. Labor typically ranges from 2 to 4 hours to replace them, which adds to the repair costs.
While you can simply replace the lousy solenoid, we recommend replacing all of them at once. If one is bad, the others are likely to have some wear and tear as well, which will cause them to fail in the future. Since the mechanic will already have access to the rest of them and the parts are fairly inexpensive, it makes sense to change them all at the same time instead of having to pay for more labor down the road if a different solenoid fails.
Accord P0700 Shift Solenoid Summary
P0700 is a generic fault code that indicates a transmission issue. It is generally followed by another fault code that points to a more specific problem within the transmission.
2000’s models of Honda Accords are prone to receiving the P0700 code and are often not accompanied by additional codes. The problem is typically caused by a bad shift solenoid which affects an automatic transmission’s ability to shift properly.
Later model Accords can also experience this issue, but it is typically more common on older vehicles with higher mileage.
Shift solenoids control automatic gear shifting. Every transmission has multiple solenoids, each of which is responsible for more than one gear. When a solenoid goes bad, it can cause hard shifting or cause the transmission to jump gears.
Additionally, depending on which solenoid is bad, it can also prevent the car from going into gear from either park or neutral.
Solenoid failure can be prevented by performing proper transmission maintenance, such as keeping the trans fluid topped off, flushing the fluid frequently, and