The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2020 E450 Transmission Limp Mode - Rough Shifts & P0700

0

Mike T. · rep 0 · May 22, 4:12 AM · 1 replies · solved · Question

Vehicle: 2020 Mercedes-Benz E450

My 2020 Mercedes-Benz E450 (W213) just went into limp mode this morning on my way to work. The car felt sluggish, and I noticed some really rough shifts, especially from 1st to 2nd gear. The check engine light also came on.

I pulled over and used my basic OBD-II scanner, and it showed a generic P0700 code, which just means 'Transmission Control System Malfunction'. It doesn't give me much to go on.

Has anyone with a newer E-Class experienced this? What was the underlying issue? I'm hoping it's not something major, but I'm worried about driving it like this. Any advice on what to check or what this might indicate?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:12 AM

0

ClearTheCode admin answer:

The P0700 code on your 2020 Mercedes-Benz E450 indicates that the Transmission Control Module (TCM) has detected a fault and has illuminated the Check Engine Light. This code is a general informational code, meaning there are more specific fault codes stored within the TCM itself that your basic OBD-II scanner cannot access.

Common Causes for Transmission Limp Mode and P0700:

  1. Low Transmission Fluid: While less common in newer sealed units, a low fluid level can cause pressure issues and erratic shifting.
  2. Faulty Valve Body/Solenoids: The valve body controls fluid flow to engage gears. Malfunctioning solenoids within it can cause rough shifts or prevent gear engagement.
  3. Transmission Speed Sensors: Incorrect readings from input or output speed sensors can confuse the TCM.
  4. Conductor Plate Issues: The conductor plate houses many of the transmission's electrical components and sensors. Failures here are common.
  5. Software Glitch: Sometimes, a simple software update or reset of the TCM can resolve intermittent issues.
  6. Internal Mechanical Failure: In more severe cases, internal clutch pack wear or other mechanical damage could be the cause.

Troubleshooting Steps (Limited without advanced tools):

  1. Check for Leaks: Visually inspect the transmission pan and surrounding areas for any signs of fluid leaks.
  2. Battery Check: Ensure your car's battery is in good health. Low voltage can sometimes cause electronic modules to malfunction.

When to See a Shop:

Driving with your transmission in limp mode is not recommended as it can potentially cause further damage. Given the complexity of modern Mercedes-Benz transmissions and the generic nature of the P0700 code, it is crucial to have your vehicle diagnosed by a Mercedes-Benz dealership or a specialized independent shop. They have the necessary diagnostic tools (like XENTRY/DAS) to communicate directly with the TCM, retrieve the specific fault codes, and accurately diagnose the underlying issue. This will allow them to determine if it's a sensor, valve body, software, or a more significant mechanical problem.

Menu

Help & account