AutoCodes – Jeep – U1420 Jeep

U1420 Jeep Code - Implausible Electronic Gear Select Signal Received

Quick Answer

This diagnostic checks for the validity and availability of the Shift Lever Position signal which is sent by the Electronic Shift Module (ESM) via a CAN message. Common causes include Faulty Electronic Shift Module (ESM), Electronic Shift Module (ESM) harness is open or shorted, Electronic Shift Module (ESM) circuit poor electrical connection. 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: U1420 Jeep indicates Implausible Electronic Gear Select Signal Received.
Common causes: Common causes include Faulty Electronic Shift Module (ESM), Electronic Shift Module (ESM) harness is open or shorted, Electronic Shift Module (ESM) circuit poor electrical connection.
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 1,255

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 May 23, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1420 Jeep Description

This diagnostic checks for the validity and availability of the Shift Lever Position signal which is sent by the Electronic Shift Module (ESM) via a CAN message. A CAN signal state is defined for each of five stable lever positions: 'Park', 'Reverse', 'Neutral', 'Drive' and 'Autostick'. CAN signal states are defined for six non-stable positions: 'Up', 'Down', 'P-R', 'R-N', 'N-D' and 'D-A'. The diagnostic checks the validity by verifying the received CAN signal state corresponds to one of the possible lever positions. The diagnostic also checks the availability by verifying the valid bit. When the Shift Lever Position signal is invalid or missing, then the Diagnostic Trouble Code (DTC) U1420 will set. The failure is detected if at least one of the following malfunctions is verified: 1) Signal Not Available Check: When the signal is not available, the ESM sends an SNA default value. If the TCM reads this value, then DTC U1420 is set. 2) Signal Invalid Value Check: If the signal value is equal to a different value than the defined values for the lever position, the Shift Lever Position value is considered not valid, then DTC U1420 is set.

OBDII Code U1420 Jeep - Implausible Electronic Gear Select Signal Received - AutoCodes.com — U1420 Jeep Code - Implausible Electronic Gear Select Signal Received

What does this mean?

What are the Possible Causes of the DTC U1420 Jeep?

Faulty Electronic Shift Module (ESM)
Electronic Shift Module (ESM) harness is open or shorted
Electronic Shift Module (ESM) circuit poor electrical connection
Faulty Powertrain Control Module (PCM)
Faulty Transmission Control Module (TCM)

How to Fix the DTC U1420 Jeep?

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 U1420 Jeep 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.

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Need Help with the Code?

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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 U1420 Jeep Code

1. What are some common symptoms of the OBDII code U1420 in a Jeep related to an implausible electronic gear select signal?

- The common symptoms include erratic shifting behavior, transmission slippage, and difficulty selecting gears.

2. What are the possible causes of the U1420 code in a Jeep?

- The U1420 code in a Jeep can be caused by a faulty transmission range sensor, damaged wiring or connectors, or a malfunctioning transmission control module.

3. How serious is the U1420 code in a Jeep?

- The U1420 code can affect the drivability of the vehicle and may lead to potential safety issues if not addressed promptly. It is recommended to address this issue as soon as possible.

4. Can I continue driving my Jeep with the U1420 code present?

- It is not recommended to continue driving your Jeep with the U1420 code present, as it can lead to further damage to the transmission and other related components.

5. How can I diagnose the U1420 code in my Jeep?

- Diagnosing the U1420 code involves using a diagnostic scanner to retrieve the code, checking the transmission range sensor and its wiring, and inspecting the transmission control module for any faults.

6. Is the repair for the U1420 code in a Jeep something I can do myself?

- The repair for the U1420 code may require advanced automotive knowledge and specialized tools, so it is recommended to have a professional mechanic diagnose and repair the issue.

7. Are there any tips for preventing the U1420 code from occurring in my Jeep?

- Regularly inspecting and maintaining the transmission system, ensuring proper fluid levels, and addressing any transmission-related issues promptly can help prevent the U1420 code from occurring.

8. How much does it typically cost to repair the U1420 code in a Jeep?

- The cost of repairing the U1420 code in a Jeep can vary depending on the underlying cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

9. Will resetting the OBDII code U1420 in my Jeep make the issue go away?

- Resetting the code may temporarily clear the warning light, but if the underlying issue causing the U1420 code is not addressed, the problem is likely to reoccur.

10. Can the U1420 code affect the fuel efficiency of my Jeep?

- Yes, the U1420 code can potentially affect the fuel efficiency of your Jeep due to the transmission-related issues it causes, leading to improper gear selection and increased fuel consumption.