Home Diagnosis and TroubleshootingOBD Diagnostic Error Codes P0700 Code: Why Is It A Cause For Concern?

P0700 Code: Why Is It A Cause For Concern?

by Jordan Harris
P0700 Code

There can be much to talk about when it comes to how technological innovations can impact a given industry. These innovations are primarily meant to help solve certain complex things we encounter daily. One of the industries that have greatly been impacted is the automobile industry. The introduction of the OBD2 scanner has made it very easy to decipher car problems. By just using the OBD2 scanner, you can retrieve your vehicle’s Diagnostic Trouble Codes. But do you know what problem each diagnostic code represents? Diagnostic P0700 code is our subject matter in this article.

Many a time’s vehicles will face mechanical problems that can be attributed to wear and tear. But can you imagine how difficult it can be to find out the real problem with your car because of the many components and systems that lead to its overall performance? Some of these mechanical problems are deep-rooted that identifying them can be a daunting task because of the many components in a vehicle.

But we can’t go dismantling every component just to get to the root cause of a problem. That is where the diagnostic codes come into play. Each diagnostic code represents a given mechanical issue. In any case, you have trouble with your car it is that simple, you only need to retrieve these codes using an OBD2 scanner. This will help you identify the problem and then fix it depending on the component represented by the trouble code. This has made vehicle repairs to be somehow an easy task since you don’t have to dismantle all components just to find the cause of vehicle malfunction.

Contents of this article entail:

What Is P0700 Code

P00700 is a diagnostic trouble code (DTC) that is associated with a malfunctioning Transmission Control System (TCS). It is also referred to as the Transmission Control Module (TCM). When there is a malfunction in the transmission control system, the check engine lights will illuminate. This will be to alert you of this problem.

Your car will also go into its failsafe mode to prevent any further damage to your engine. You can identify this specific problem by checking your vehicle using the OBD2 scanner. If the scanner displays the diagnostic trouble code P0700, then it refers to this problem. As a matter of urgency and to prevent any further damage to your engine, you should have it fixed immediately.

In most modern vehicles, there is a transmission control module. This module is usually denoted as TCM. Among the roles of this module in a car is to detect and report any faults in an automatic transmission vehicle. It then sets a specific code that is then relayed to the Engine Control Module (ECM).

The ECM in turn will indicate that a vehicle component isn’t working properly. The TCM is always in constant communication with the ECM. When both modules detect that something is wrong with the transmission, OBD2 code P0700 appears.

Causes Of The P0700 Code To Appear

A transmission control module is a collection of circuit boards and microprocessors. It’s responsible for activating solenoids, which then direct the flow of pressurized hydraulic fluid (transmission fluid) down the right channel to engage a clutch, lock, or unlock a planetary gear set.

Before you can fix any problem related to the Transmission Control Module, you need to identify some of the possible causes of this malfunction. This can help you not to find yourself fixing the wrong parts. Failure can always happen because of several reasons that include:

Faulty Transmission Control Module

The Transmission Control Module has the responsibility of monitoring other components of the transmission including transmission sensors and actuators. The TCM monitors the functionality of the transmission to ensure it works correctly. When the TCM becomes faulty, it could show errors even when nothing is wrong.

Transmission Valve Body Fault

The transmission functions by transmitting fluids to different parts of the engine to help in the shifting of gears and acceleration. The valve bodies act as the nerve center of the transmission.

The valves make sure that the right amount of fluid is transmitted to where it is required. Any fault with these valves can lead to malfunction inside the transmission causing the error code to appear.

Shift Solenoid Issues

The shift solenoids help in controlling the flow of hydraulic fluids inside the transmission. It is the one that enables you to shift gears accordingly with ease. Shift solenoids can break down leading to problems with fluid distribution. This can eventually lead to the overall failure of the transmission.

Open Or Short In Wire Harness

Modern cars depend on several electrical systems to help provide power to the transmission and all its sensors. A short in the wiring or an open connection can cause electrical problems hence causing the transmission to malfunction.

Symptoms Of The P0700 Code

There are several signs that the TCM is failing. If you detect any of these, it is best to have it checked by a professional before there is damage to your transmission. Repairing or replacing the transmission can be very expensive.

Transmission Overheating

Transmissions can overheat for several reasons, including a defective TCM. Pulling heavy loads, heavy acceleration, the transmission stuck in a lower gear while accelerating to higher speeds.

P0700 code

Once a transmission overheats, the components and the transmission fluid are less efficient, which may cause further problems. Have the TCM checked by a qualified transmission technician as well as have the transmission fluid changed. So, be wary of when you need a Ford transmission fluid change and how often do you change transmission fluid.

Shift Lock In The Same Gear

A sure sign that the TCM is malfunctioning is when the transmission is stuck in the same gear and will not shift up or down as engine speed changes. For example, if the transmission is stuck in high gear, you may not speed up from a standstill position because of the high torque required.

Transmission stuck in 1st gear will limit the maximum speed you can attain even with the engine revving at a high RPM. The transmission should downshift as the car decelerates.

Gear Is Stuck In Neutral

Another example of a malfunctioning TCM is when the transmission is stuck in the neutral gear. Regardless of which position the gear shift is placed in, the car will not move since the transmission is stuck in the neutral position.

Your car is not driveable in this situation and must be repaired. Car owners will have to arrange for their vehicle to be transported to a garage for possible repairs to the transmission and TCM module replacement.

Cannot Shift Properly Into Higher Gears

The TCM shifts gears as your car gradually increases speed. Each gear has a top-end speed, and the transmission should shift to the next gear as this speed is reached.

When the shift does not occur, your engine continues to revolve at a high RPM, without the corresponding increase in ground speed. Your vehicle may never allow you to reach highways speeds under these conditions, which could be dangerous to yourself and other high-speed traffic.

Gear Shift Have Problems Downshifting

The TCM (Transmission Control Module) is also responsible for downshifting the transmission as the ground speed gradually declines. Once you come to a stop at a stop sign or stoplight, the TCM should have shifted the transmission into 1st gear.

The transmission should be ready to accelerate. If the downshift does not take place, the transmission may still be in a higher hear, making it very difficult to accelerate from a stopped position. In some situations, the high gear position may prevent the car from moving at all from a stationary position.

Delayed Shifting

Your car’s TCM and transmission are designed to shift gears within specific parameters of engine RPM and ground speed. If the transmission shifts gears slowly, there is a loss of momentum, and the car can even slow down during gear changes.

If delayed shifting occurs while climbing a hill, the impact will be even worse. A bad TCM can cause the gears to change slowly and have a dramatic effect on the performance of the vehicle.

Poor Fuel Economy

The TCM, transmission, and engine are designed to work in unison to deliver maximum power at maximum fuel efficiency. Any time the TCM is not performing properly, the fuel economy can be impacted.

For example, a transmission that shifts too late or not at all causes the engine to work harder at a less than the optimal degree. In most cases, more fuel is consumed, lowering the miles per gallon efficiency usually delivered by your car.

Check Engine Light

The check engine light can be illuminated for many reasons, and drivers should have their vehicles checked by a registered mechanic. Often there is a problem with the TCM module if the check engine light is on, and your transmission displays some of the above symptoms.

A mechanic may use a scan tool to check the diagnostic trouble codes for a sign of what is causing the problem. A P0700 error code usually indicates a problem with the TCU (Transmission Control Unit).

Low Transmission Fluid

Low transmission fluid can cause erratic shifting. Symptoms include spikes in RPM levels during shifts, grinding noises, slipping in and out of gears, and erratic shifts. If you have these symptoms, the transmission fluid may be low.

Check for telltale signs of fluid leaks under your car. You may also notice the transmission overheating, such as a burning smell since it must work harder with less fluid. Always pull over and avoid serious damage to the internal transmission components.

Transmission Gear Slipping

As your transmission changes gears while accelerating, the transmission may fall back to the lower gear, which indicates gear or transmission slippage. Low transmission oil or a faulty transmission control module could be the cause.

Avoid driving the vehicle long distances and under heavy loads or up steep grades. With gears slipping, acceleration to highway speeds may not be possible, which could cause a dangerous situation on the highway with other high-speed traffic. The transmission internal components could also be damaged.

How To Diagnose Code P0700

When you start noticing some of the symptoms that point out to failure within your transmission control system, the next thing is always to try to decipher the probable cause. While you can have the problem fixed by an experienced mechanic, you may want to try to identify and fix the problem yourself. If this is the road, you would prefer to take and you much confident with your capability, then here are the steps you can explore:

STEP 1: Use OBD2 Scanner

The first thing to do is to get your OBD2 scanner to help you confirm if the problem is associated with the transmission. Just because you are experiencing stalling and shifting problems with your car does not automatically point out a transmission fault.


You will have to confirm this using the OBD2 scanner. If you can and find a diagnostic trouble code P0700, then it is for sure a transmission-related problem. You have to also keep in mind that they may sometimes also point out engine-related problems. If this is the case, then it will be the beginning of some serious work.

STEP 2: Clear The Code And Test Drive The Car

Before you begin dismantling your transmission or the engine, you have to confirm that the code wasn’t a fluke. You may want to carry out one more step to confirm that the code is correctly pointing out a genuine problem.

You can clear the code then drive your car for a while. If the check engine lights illuminate once again, use your OBD2 scanner one more time to confirm if the code comes back again. If the P0700 code comes back, then you have all the probability pointing towards a transmission problem.

STEP 3: Inspect The Transmission

The first and the easiest thing to do is to check for any visible damage to the transmission. This includes inspecting the valve body and the shift solenoids. You must also inspect the electrical wiring to make sure that all the electrical connections are in perfect shape. This is because wrong wiring can also lead to transmission failure that will trigger the check engine lights and produces P0700 code on scanning.

STEP 4: Utilize Live Scan Features

If your visual inspection bears no fruits, then you have to move to the next step. You will have to utilize the application of the live scan devices to see what might be going on inside the transmission.

P0700 Code

If the root of the problem will point out to something right inside the transmission, then that will be a complex job that can only be done by a professional mechanic. The live scan feature can help you identify if it is a mechanical problem or an electrical problem involving sensor failure.

Common Mistakes In Fixing P0700 Code

The most common mistake often made when diagnosing the symptoms of a P0700 code is to misidentify the problem as a mechanical issue involving the transmission itself. As it is known that transmission replacements are very expensive. This means that any misdiagnosis will not only fail to cure the problem but you shall have spent a lot of money having unnecessary work done.

If by any chance you suspect that your transmission control module is the source of the problem then get that OBD2 scanner, get those codes to read, and look for a diagnostic trouble code P0700 or any other codes related to a faulty transmission control module. A TCM problem can be easily fixed within a very short time.

Another common mistake is failing to check the wire harness thoroughly. You may end up replacing a perfectly fine TCM thinking it’s the problem leaving out the wire harness issue undressed.

How Serious Is A TCM Malfunction (P0700 Code)

Issues related to transmission malfunction should always be treated with uttermost urgency. This is because a small problem can easily breed into other problems that can lead to the total breakdown of the engine and the transmission. The cost that can be involved in engine and transmission rebuilds or replacement can be unimaginable.

If the problem is just a faulty sensor, the car will just operate fine. However, if the problem is emanating right inside the transmission itself, you just have to fix it immediately because it may cause more harm to the general operation of your car.

The biggest danger involving transmission failure is when you start having trouble shifting. If the transmission fluid isn’t flowing smoothly to all the parts of the transmission, then this can result in severe mechanical problems.

How Can I Fix P0700 Code

To fix the diagnostic trouble P0700 code, there are many steps that you will have to carry out in an attempt to try to troubleshoot the error. These steps include:

  • Using a Scan Tool, compare the RPM input speed and compare the RPM output speed on a flat, smooth surface.
  • When comparing the torque converter RPM to the Input Shaft RPM, keep an eye out for a Converter Slip Speed PID or Parameter Identification. To test this, gradually depress the throttle, starting above 45mph. If it is functioning properly, the Slip Speed should never be above 50 RPM. If the Slip Speed increases when gradually depressing the throttle while above 45 mph, then you know you have a slipping Converter Clutch. In case you are doing this test and the Slip Speed stays steady but the transmission Output Shaft Speed and MPH start to decrease, then you know that you have an internally slipping transmission (usually because of worn Clutch Packs or Sprag Clutches.)
  • Check transmission fluid to make sure that it is not dirty (should be red, not black) and at a sufficient level. Replace if necessary.
  • If these steps do not clear your Check Engine Light, you may need to visit a mechanic because there may be internal electrical issues.

Cost Of Replacing Transmission Control Module

The average transmission control module (TCM) repair cost is $300. This is slightly lower than the replacement cost. In this case, the TCM (Transmission Control Module) may just need resetting if it is not damaged.

A damaged TCM must be replaced. It is worth a try. You may be able to save a significant amount of your transmission repair costs. A faulty transmission or engine repair is the most significant repair on a car.

But sometimes, the TCM may have been completely damaged and need a replacement. The replacement cost is between $250 and $1250, depending on the car model and labor costs.

The average cost of the transmission control module is between $200 and $750. This will greatly depend on the type of parts to be used. Aftermarket parts can be much cheaper than OEM parts. The labor cost may range between $50 and $500.

The costs associated with repairing or replacing the transmission control module in your vehicle depend on many factors, such as your vehicle’s design and type, the brand, and the parts to be replaced.

In some vehicles, the transmission control module is even installed inside the transmission. This creates the problem that you have to take it apart and this can be very costly.

The other thing to consider is that after the transmission control module replacement, it needs to be programmed by a diagnostic tool. You most often need to do this at a workshop, and nothing you can do yourself with basic knowledge.

P0700 Code: Conclusion

You’ll probably never have to replace or repair the TCM over the lifespan of your car. However, in some rare cases, your TCM just like any other component in your car will fail and trigger the P0700 code. In case of a faulty TCM, it’s essential to contact a professional mechanic for immediate diagnosis of the P0700 code. This is because ignoring it may breed other costly problems.

A vehicle’s Transmission Control Module is a vital component of any road-going vehicle that runs on an automatic transmission system. Most modern automobiles come with a TCM unit, which is handy compared to relying on mechanical or hydraulic control.

Similar systems are used in conjunction with various semi-automatic transmissions, purely for clutch automation and actuation. A TCU in a modern automatic transmission generally uses sensors from the vehicle, as well as data provided by the engine control unit (ECU), to calculate how and when to change gears in the vehicle for optimum performance, fuel economy, and shift quality.

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