AutoCodes – Generic – P1D20

P1D20 Code - Multi Module Handshake Failure

Quick Answer

The purpose of the diagnostic is to monitor the question-answer CAN communication between the Electronic Shifter Module (ESM) and the Transmission Control Module (TCM) by comparing the ESM response to the expected value within the TCM software. Common causes include Faulty Electronic Shifter Module (ESM) Internal Error, Faulty Transmission Control Module (TCM) Internal Error. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1D20 indicates Multi Module Handshake Failure.
Common causes: Common causes include Faulty Electronic Shifter Module (ESM) Internal Error, Faulty Transmission Control Module (TCM) Internal Error.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 2,798

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1D20 Description

The purpose of the diagnostic is to monitor the question-answer CAN communication between the Electronic Shifter Module (ESM) and the Transmission Control Module (TCM) by comparing the ESM response to the expected value within the TCM software. The TCM sends two randomly generated values to the ESM and the ESM is expected to answer with a value calculated based upon these two random numbers. The TCM commands the ESM to reset if one of the following conditions occurs: No answer received within a calibrated amount of time, received answer is incorrect and is the same as the previous answer or the received answer is incorrect and is not the same as the previous answer.

OBDII Code P1D20 - Multi Module Handshake Failure - AutoCodes.com — P1D20 Code - Multi Module Handshake Failure

What does this mean?

What are the Possible Causes of the DTC P1D20?

Faulty Electronic Shifter Module (ESM) Internal Error
Faulty Transmission Control Module (TCM) Internal Error

How to Fix the DTC P1D20?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1D20 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P1D20 code?

Need more information on how to fix the P1D20 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1D20 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P1D20 Jeep — Multi Module Handshake Failure

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1D20 Code

1. What are the common symptoms of OBDII code P1D20 (Multi Module Handshake Failure)?

The common symptoms of OBDII code P1D20 include issues with various vehicle modules not communicating properly, resulting in warning lights on the dashboard, erratic behavior of electronic components, and possible drivability issues.

2. What are the possible causes of OBDII code P1D20 (Multi Module Handshake Failure)?

Possible causes of OBDII code P1D20 include faulty wiring or connectors, software glitches in the vehicle's control modules, a weak battery, or a malfunction in one of the vehicle's electronic control units.

3. How can I diagnose OBDII code P1D20 (Multi Module Handshake Failure)?

Diagnosing OBDII code P1D20 may involve using an OBDII scanner to retrieve the specific fault codes, checking for loose or damaged wiring connections, inspecting the vehicle's control modules for any signs of malfunction, and performing a system reset if needed.

4. What are some repair tips for OBDII code P1D20 (Multi Module Handshake Failure)?

Repair tips for OBDII code P1D20 may include repairing or replacing faulty wiring or connectors, updating the software in the vehicle's control modules, ensuring the battery is in good condition, and performing a relearn procedure to reset the system.

5. Can I drive my vehicle with OBDII code P1D20 (Multi Module Handshake Failure)?

It is not recommended to drive your vehicle with OBDII code P1D20, as it may cause further damage to the vehicle's electronic systems and potentially affect its drivability. It is best to address the issue promptly to avoid any safety risks.

6. How much does it cost to repair OBDII code P1D20 (Multi Module Handshake Failure)?

The cost of repairing OBDII code P1D20 can vary depending on the underlying cause of the issue. Simple fixes such as repairing wiring connections may be relatively inexpensive, while more complex issues like replacing control modules can be more costly.

7. Can OBDII code P1D20 (Multi Module Handshake Failure) be a false alarm?

While it is possible for OBDII codes to be triggered by temporary glitches, OBDII code P1D20 typically indicates a legitimate issue with the communication between vehicle modules. It is important to investigate the cause of the code to ensure the vehicle's proper functioning.

8. Will resetting the OBDII code P1D20 (Multi Module Handshake Failure) make it go away permanently?

Resetting the OBDII code P1D20 may temporarily clear the code, but if the underlying issue is not addressed, the code is likely to reappear. It is crucial to diagnose and repair the root cause of the problem to prevent the code from returning.

9. Can a DIY enthusiast fix OBDII code P1D20 (Multi Module Handshake Failure) at home?

Depending on the cause of OBDII code P1D20, some DIY enthusiasts may be able to address the issue at home by checking and repairing wiring connections, updating software, or performing basic troubleshooting steps. However, more complex issues may require professional assistance.

10. How long does it take to repair OBDII code P1D20 (Multi Module Handshake Failure)?

The time it takes to repair OBDII code P1D20 can vary based on the specific cause of the issue and the complexity of the repair. Simple fixes may be completed in a short amount of time, while more involved repairs could take several hours or longer.