P0700 – Transmission control system (MIL request)

The P0700 OBD2 code is a relatively generic code—and one that you should take seriously. It indicates a malfunction in the transmission control system, preventing your car from changing gears properly, making you a hazard to yourself and others on the road.

Fixes for the P0700 code may be specific to your vehicle’s make and model. Take this into account as you’re going through your diagnosis. Follow any advice outlined in your manual over the general diagnosis steps laid out below.

The P0700 code solutions range from simply replacing your transmission fluid to an entire overhaul of your transmission system. The good news is, an OBD2 scan tool gives you all the data you need to diagnose this trouble code.

P0700 code definition

Transmission control system TCS malfunction

Here's where you can get a thorough understanding of the P0700 OBD2 code
If you want to learn about the P0700 OBD2 code, this is the right place

What does P0700 mean?

The P0700 OBD2 code triggers when a malfunction is detected in your transmission controls. Most modern cars have a specific control module for the automatic transition system called the transmission control module, or TCM.

The TCM’s role in your system is to monitor the transmission system’s sensors and send that data to the engine control module (ECM). If any issues are detected when the ECM reads this data, the P0700 trouble code is activated. Along with the check engine light, activation of this code triggers a failsafe mode. Your system will remain in this mode until the fault has been repaired and regular operation can resume.

The P0700 OBD2 code only tells you there’s some problem in your transmission system. You’ll need to dig a bit deeper to find the problem’s exact source, which makes your OBD2 scan tool your best friend when you need to fix a P0700 code.

What are the symptoms of the P0700 code?

You will likely notice drivability issues with code P0700, mainly caused by slips in the transmission. The most common symptoms include:

The symptoms of the p0700 code
The five symptoms of the P0700 code
  • Activation of the check engine light,
  • Activation of fail-safe mode,
  • Hesitation or other problems when changing gears,
  • Stalls and rough driving,
  • Reduced gas mileage.

What are the causes of P0700?

  • Shift solenoid is defective,
  • The engine coolant sensor is defective,
  • Short or open circuit in TCM,
  • Faults in the transmission valve body,
  • TCM is faulty,
  • PCM is faulty (rare).

How serious is the P0700 code?

The P0700 is very serious. Issues with your transmission control system can prevent your car from changing gears, potentially making your car dangerous to drive. You should stop immediately driving when P0700 activates and avoid driving (aside from controlled diagnostic road tests) until you’ve repaired the problem.

How to diagnose the P0700 code?

While P0700 is a generic powertrain code, the specific fix can vary depending on your vehicle. Check your car’s manual and search for technical service bulletins applicable to your make and model before starting your diagnosis.

OBD2 scan tool is the best way to diagnose the errorr P0700 codes
To diagnose the P0700 code, OBD2 scanner is the best choice.

Tools you’ll need: OBD2 scan tool.

Here are the steps:

Steps to diagnose the p0700 code
6 steps to diagnose the p0700 code.
  1. Scan for other trouble codes. Most of the time, P0700 is activated, but it isn’t the only trouble code. You will commonly see codes related to the shift solenoid. Diagnose these codes first. Since they’re more specific, it’s often easier to locate the issue.
  2. Use your scan tool to read the freeze frame data. Pay particular attention to the RPM, throttle position, and engine torque readings. Compare the RPM’s input speed and output speed.
  3. Depress the throttle slowly, starting above 45mph. Read the freeze frame data as you do this. The Slip Speed should never go over 50rpm. If it increases, the converter clutch is slipping. Alternatively, if the Slip Speed is steady, but the output shaft speed decreases, the transmission is slipping internally. Check your clutch packs and sprag clutches for wear.
  4. Check your transmission fluid. It should be read and clear of debris, and the reservoir should be filled sufficiently. Also, check for signs of transmission fluid on your engine components or pooled fluid beneath your car, which could indicate a leak.
  5. Drain the transmission fluid and check it for metal flakes. These are from mechanical wear in the transmission and are often seen when the transmission is failing. If these flakes are present, they may have clogged the solenoid, causing it to fail. Metal flakes may also indicate your transmission needs to be rebuilt or replaced.
  6. Inspect all the wiring related to the transmission system. Replace any wires that are damaged, frayed, or shorted.

Common mistakes to avoid while diagnosing the P0700 code

The biggest mistake is to diagnose based on your car’s symptoms rather than reading the trouble codes. The drivability issues associated with P0700 can be misinterpreted as engine misfires. With a serious code like this, it’s crucial to conduct a thorough diagnosis using an OBD2 scan tool and ensure you’ve fixed the issue.

What should you do to fix the code P0700?

  1. Replace any faulty or damaged wires found during your diagnosis. Ensure all connections are secure.
  2. Locate the source of any transmission fluid leaks and replace the faulty component.
  3. Drain your transmission fluid, then remove and replace the filter. Examine both the fluid and filter for debris. If any is present, flush your system and put in fresh transmission fluid. If there are many metal flakes in your transmission fluid, take your car to a transmission expert. There is a more serious issue in your system that needs to be addressed.
  4. Replace the transmission shift solenoid if it is dirty or damaged.
  5. Clear all OBD2 codes and take a test drive, replicating the conditions of the initial failure. If the P0700 code comes back, you may have more complicated electrical problems. Take your car to a mechanic for further diagnosis.

Tips to avoid P0700 in the future

Proper maintenance of your transmission system is the best way to avoid the P0700 code. Check your transmission fluid regularly and replace it when it gets dirty. If you see drips or puddles of transmission fluid in your garage or driveway, locate and fix the leak right away, even if no trouble codes are active.

Read more: P0440: Meaning, Symptoms, Causes, Diagnostics, and Fixes.