AutoCodes – RAM – U1421 RAM

U1421 RAM Code - Implausible Ignition Key Off Time Received

Quick Answer

The Body Control Module (BCM) monitors the time the ignition is in the off or accessory position between key cycles and then broadcasts the signal called Ignition Off Time (IOT) via the CANC Bus. Common causes include Faulty Body Control Module (BCM), Body Control Module (BCM) harness is open or shorted, Body Control Module (BCM) 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: U1421 RAM indicates Implausible Ignition Key Off Time Received.
Common causes: Common causes include Faulty Body Control Module (BCM), Body Control Module (BCM) harness is open or shorted, Body Control Module (BCM) 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 3,465

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 U1421 RAM Description

The Body Control Module (BCM) monitors the time the ignition is in the off or accessory position between key cycles and then broadcasts the signal called Ignition Off Time (IOT) via the CANC Bus. The Powertrain Control Module (PCM) saves the value from a previous key cycle into powerdown flash and if certain When Monitored conditions are met compares to the current value. If the Set Conditions are met, then a fault U1421 is set indicating the timer is stuck. If this fault becomes active the PCM will light the MIL light immediately. If the MIL is set and the fault goes stored the PCM turns off the MIL after 3 consecutive drive cycles. If the difference between two Ignition Off Times (IOT) sent from the BCM to the PCM during two separate diagnostic decisions is less than 3 minutes for 5 consecutive decisions this fault will set.

OBDII Code U1421 RAM - Implausible Ignition Key Off Time Received - AutoCodes.com — U1421 RAM Code - Implausible Ignition Key Off Time Received

What does this mean?

What are the Possible Causes of the DTC U1421 RAM?

Faulty Body Control Module (BCM)
Body Control Module (BCM) harness is open or shorted
Body Control Module (BCM) circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC U1421 RAM?

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 U1421 RAM 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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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 U1421 RAM Code

1. What are the common symptoms of OBDII code U1421 RAM?

The common symptoms of U1421 RAM include issues with the vehicle's ignition system, such as difficulty starting the engine, stalling, or persistent misfires.

2. What can cause the OBDII code U1421 RAM to trigger?

The U1421 RAM code is typically triggered when the ignition key off time received by the Powertrain Control Module (PCM) is deemed implausible, indicating a communication error between the ignition system components.

3. How serious is the U1421 RAM code?

While the U1421 RAM code may not cause immediate danger, it can lead to performance issues and potential reliability concerns if left unresolved. It is recommended to address this code promptly.

4. How can I diagnose the U1421 RAM code?

Diagnosing the U1421 RAM code involves using an OBDII scanner to retrieve the code, inspecting the ignition system components for any visible damage or loose connections, and testing the key off time signals for accuracy.

5. What are some repair tips for resolving the U1421 RAM code?

Repair tips for U1421 RAM may include checking and repairing any faulty wiring or connectors related to the ignition system, resetting the PCM, or replacing the ignition key if necessary.

6. Can a DIY enthusiast fix the U1421 RAM code?

While some DIY enthusiasts may be able to address the U1421 RAM code by following repair guides and using basic tools, it is recommended to consult a professional mechanic for accurate diagnosis and repair to ensure the issue is resolved correctly.

7. Is it safe to continue driving with the U1421 RAM code present?

It is generally not recommended to drive with the U1421 RAM code present, as it can lead to potential performance issues and cause further damage to the ignition system components. It is best to address the code as soon as possible.

8. How much does it typically cost to repair the U1421 RAM code?

The cost of repairing the U1421 RAM code can vary depending on the underlying cause, the extent of the repairs needed, and the labor rates of the repair shop. It is advisable to obtain quotes from different shops for a more accurate estimate.

9. Can weather conditions affect the triggering of the U1421 RAM code?

Extreme weather conditions, such as extreme cold or heat, can potentially impact the ignition system components and lead to communication errors that trigger the U1421 RAM code. It is essential to keep the vehicle well-maintained to prevent such issues.

10. How long does it typically take to repair the U1421 RAM code?

The time required to repair the U1421 RAM code can vary depending on the complexity of the issue and the availability of replacement parts. In some cases, the repair can be completed within a few hours, while more extensive repairs may take longer.