AutoCodes – Generic – P1821

P1821 Code - Shift Fork Position Sensor 1 System Voltage High Range Out

Quick Answer

The Transmission Control Module (TCM) monitors the Shift Fork Position Sensor 1. Common causes include Faulty Shift Fork Position Sensor 1, Shift Fork Position Sensor 1 harness is open or shorted, Shift Fork Position Sensor 1 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: P1821 indicates Shift Fork Position Sensor 1 System Voltage High Range Out.
Common causes: Common causes include Faulty Shift Fork Position Sensor 1, Shift Fork Position Sensor 1 harness is open or shorted, Shift Fork Position Sensor 1 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 13,341

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 Jan 30, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1821 Description

The Transmission Control Module (TCM) monitors the Shift Fork Position Sensor 1. The TCM sets the OBDII code when the Shift Fork Position Sensor 1 is not to factory specifications.

OBDII Code P1821 - Shift Fork Position Sensor 1 System Voltage High Range Out - AutoCodes.com — P1821 Code - Shift Fork Position Sensor 1 System Voltage High Range Out

What does this mean?

What are the Possible Causes of the DTC P1821?

Faulty Shift Fork Position Sensor 1
Shift Fork Position Sensor 1 harness is open or shorted
Shift Fork Position Sensor 1 circuit poor electrical connection

How to Fix the DTC P1821?

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 P1821 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 P1821 code?

Need more information on how to fix the P1821 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1821 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P1821 Mitsubishi — Shift Fork Position Sensor 1 System Voltage High Range Out

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 P1821 Code

1. What are the common symptoms of OBDII code P1821 (Shift Fork Position Sensor 1 System Voltage High Range Out)?

The common symptoms of code P1821 may include difficulty shifting gears, transmission slipping, and illuminated warning lights on the dashboard.

2. What can cause OBDII code P1821 to trigger?

Code P1821 is typically triggered by a malfunction in the shift fork position sensor circuit, a faulty sensor, or issues with the wiring and connectors associated with the sensor.

3. How serious is OBDII code P1821 (Shift Fork Position Sensor 1 System Voltage High Range Out)?

While the severity of the code may vary, it is important to address it promptly to prevent potential transmission damage and ensure safe driving conditions.

4. How can I diagnose the cause of OBDII code P1821?

Diagnosing code P1821 involves using a scan tool to retrieve the code, inspecting the shift fork position sensor and its circuit for any visible damage, and testing the sensor's voltage levels.

5. Can I drive my vehicle with OBDII code P1821 present?

It is not recommended to drive your vehicle with code P1821 present, as it can lead to transmission issues and potentially cause further damage if left unaddressed.

6. How can I repair OBDII code P1821 (Shift Fork Position Sensor 1 System Voltage High Range Out)?

Repairing code P1821 involves replacing the faulty shift fork position sensor, repairing any damaged wiring or connectors, and clearing the code with a scan tool.

7. Are there any DIY tips for fixing OBDII code P1821?

While some DIY enthusiasts may attempt to replace the shift fork position sensor themselves, it is recommended to seek professional help to ensure the repair is done correctly.

8. How much does it typically cost to repair OBDII code P1821?

The cost of repairing code P1821 can vary depending on the extent of the damage, the cost of parts, and labor charges from a professional mechanic.

9. Can OBDII code P1821 be intermittent?

Yes, code P1821 can sometimes be intermittent, but it is still important to address the underlying issue to prevent potential transmission problems in the future.

10. How long does it take to repair OBDII code P1821?

The repair time for code P1821 can vary depending on the accessibility of the sensor and any additional repairs needed, but it is typically a relatively quick fix for experienced mechanics.