Transmission Control System MIL Request – P0700 [Meaning, Causes, & How To Fix] 

The P0700 OBD2 code is a fairly common code that you should pay close attention to. It is the transmission control mil request system code. 

This code usually denotes a problem with the transmission control system, which prevents your automobile from changing gears correctly and puts you and other drivers on the road in danger.

The make and model of your car may have a bearing on the P0700 code fixes.

In this post, we help you understand what a transmission control system mil request code is all about and the various steps on how you can fix this error.

Transmission Control System MIL Request - P0700

What Does Transmission Control System Mil Request Mean?

The transmission control module (TCM) is a particular control module for the automatic transition system used in the majority of contemporary vehicles.

This transmission error code is P0700, and it is diagnosed using the information provided by an OBD2 diagnostic tool. 

Your system’s TCM is used for tracking all the sensors in the transmission system and providing data to the engine control module (ECM).

Therefore, if there is any problem found when the ECM reads this data, the P0700 error code gets to be activated.

This code’s activation also activates the check engine light and a failsafe mode. As long as the issue is not fixed, your system will continue to operate in this mode.

Common Causes of Transmission Control System Mil Request

  1. Transmission control system failure
  2. Engine coolant sensor failure
  3. Transmission fluid contamination or low levels
  4. Short circuits in the wiring
  5. Transmission problems
  6. Faulty shift solenoids

How to Diagnose the Transmission Control System MIL Request (P0700 Error Code)

Step 1: Scan for Further Error Codes

A problem in your car usually triggers p0700, although it isn’t the only difficulty code found in automobiles. Codes linked to the shift solenoid are prevalent.

Therefore, you need to first identify these codes. This is to make it easier for you to know what triggered the transmission control system mil request code. 

Step 2: Read the Freeze Frame Data with Your Scan Tool

Pay close attention to the RPM, throttle position, and engine torque measurements. Contrast the input and output speeds of the RPM.

Step 3: Slowly Press the Throttle After Reaching 45 Mph

While doing so, read the freeze frame data. The Slip Speed should never be higher than 50rpm. If it rises, it means the converter clutch is faulty. 

Also, if the Slip Speed remains constant while the output shaft speed falls, then the gearbox is slipping internally. Therefore, you need to get your clutch packs and sprag clutches examined. 

Step 4: Examine your Transmission Fluid

It should be clean, and free of dirt, and the reservoir should be appropriately full. In addition, look for evidence of transmission fluid on engine components or pooled fluid beneath your vehicle, which might suggest a leak.

Step 5: Check the Transmission Fluid for Metal Flakes

These metal flakes in fluid happen as a result of mechanical wear in the transmission and are frequently noticed when your transmission fails. 

If such particles are detected, they may have clogged the solenoid, leading it to fail. Metal flakes could also be an indication that your transmission needs to be replaced.

Step 6: Examine all Transmission System Wiring

Check for damaged or disconnected wires. When you identify anyone that is broken or disconnected, make sure to replace or reconnect it back.

Common Mistakes in Diagnosing P0700

When diagnosing the symptoms of a P0700 code, the most typical error is misidentifying the problem as a mechanical issue with the transmission itself.

Transmission repairs, as you are surely aware, are significantly more expensive than replacing a single computer. Not only will this sort of misdiagnosis fail to solve the problem, but it will also cost you a lot of money.

If you feel your TCM is creating difficulties with your car, get your codes to read and search for P0700 or other TCM-related codes.

If it is a TCM issue, you will be able to resolve it fast and simply. Another common blunder is failing to give the wiring harness a thorough inspection. This may lead to replacement.

How to Fix Transmission Control System Mil Request

  1. Replace any damaged wire discovered during your diagnosis. Make certain that all connections are secure.
  2. Locate the cause of any transmission fluid leaks and replace the defective component.
  3. Replace your filter. Examine the fluid and the filter for debris. If it is clogged or damaged, then you need to drain the transmission fluid. After cleaning or replacing the filter, you can then replace the drained fluid. If you see a lot of metal flakes in your transmission fluid, take your vehicle to a transmission specialist. There is a more significant problem in your system that must be addressed.
  4. If the transmission shift solenoid is unclean or broken, replace it.
  5. Clear any OBD2 codes and go for a test drive. If the P0700 error code appears, you may have more serious electrical problems. Take your vehicle to a mechanic for further evaluation.


How critical is the P0700 error code?

The P0700 is a pretty severe warning alert. Transmission control system problems might prohibit your vehicle from changing gears, potentially making it dangerous to drive.

When P0700 appears, you should immediately stop driving and avoid driving (except for controlled diagnostic road testing) until the problem has been resolved.

Read: C0561 Chevy


The transmission control system mil request is the P0700 error code that appears when there is an issue with your transmission system.

This code’s activation brings on the check engine light and the most likely reason it appears is that the transmission control module detects a problem in the transmission system. This can prevent you from changing gears while driving.

Therefore, to fix this error message, you need to follow the steps mentioned in this post. Because, until the fault is fixed and normal functioning can resume, your machine will remain in this state.