AutoCodes – GMC – P0843 2017 GMC Sierra

P0843 2017 GMC Sierra Code - Transmission Fluid Pressure Switch 1 Circuit High Voltage

Quick Answer

The Transmission Fluid Pressure (TFP) switch 1 is part of the control solenoid valve assembly, which has no serviceable parts. Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve Assembly. 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: P0843 2017 GMC Sierra indicates Transmission Fluid Pressure Switch 1 Circuit High Voltage.
Common causes: Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve Assembly.
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 225

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 Aug 02, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0843 2017 GMC Sierra Description

The Transmission Fluid Pressure (TFP) switch 1 is part of the control solenoid valve assembly, which has no serviceable parts. The Transmission Control Module (TCM) supplies a signal circuit to the TFP Switch 1. The TFP Switch 1 has an internal case ground. TFP Switch 1 is normally closed or LOW. When oil pressure is present at the TFP Switch 1, the switch is open or HIGH. The normally high clutch pressure control (PC) solenoid 2 controls pressure to the 3-5 reverse clutch regulator valve. The TCM monitors the TFP switch 1 to determine the position of the 3-5 reverse clutch regulator valve. When the 3-5 reverse clutch is commanded OFF, pressure is present on the TFP switch 1. When the 3-5 reverse clutch is commanded ON, the 3-5 reverse clutch regulator valve moves and pressure to the TFP switch 1 is exhausted through the 3-5 reverse clutch regulator valve. The Diagnostic Trouble Code (DTC) will be set when the TCM detects that the TFP switch 1 signal voltage remains HIGH after the 3-5-R clutch transitions from a LOW pressure state to a HIGH pressure state. The TCM counts each incident. The DTC sets when 35 counts are accumulated.

OBDII Code P0843 2017 GMC Sierra - Transmission Fluid Pressure Switch 1 Circuit High Voltage - AutoCodes.com — P0843 2017 GMC Sierra Code - Transmission Fluid Pressure Switch 1 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0843 2017 GMC Sierra?

Low transmission fluid level
Dirty transmission fluid
Faulty Transmission Control Solenoid Valve Assembly
Transmission Control Solenoid Valve Assembly harness is open or shorted
Transmission Control Solenoid Valve Assembly circuit poor electrical connection

How to Fix the DTC P0843 2017 GMC Sierra?

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 P0843 2017 GMC Sierra 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 P0843 2017 GMC Sierra code?

Need more information on how to fix the P0843 2017 GMC Sierra code? Get Access to Factory Service Manuals

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 P0843 2017 GMC Sierra Code

1. What does the OBDII code P0843 mean on a 2017 GMC Sierra?

P0843 indicates a "Transmission Fluid Pressure Switch 1 Circuit High Voltage," meaning the transmission control module (TCM) has detected an unusually high voltage signal from the pressure switch circuit.

2. What are common symptoms of code P0843 in a 2017 GMC Sierra?

Symptoms may include harsh or delayed shifting, transmission slipping, the vehicle entering limp mode, and the check engine light being illuminated.

3. What causes the P0843 code on a GMC Sierra?

Common causes include a faulty transmission fluid pressure sensor, damaged or corroded wiring, a short circuit, a poor electrical connection, or low transmission fluid levels.

4. Can I drive my 2017 GMC Sierra with a P0843 code?

Driving with this code is not recommended as it could cause further damage to the transmission or affect the vehicle's performance due to improper shifting.

5. How do I fix the P0843 code on my GMC Sierra?

Repairs may involve inspecting and repairing wiring or connectors, replacing the transmission fluid pressure sensor, or addressing transmission fluid issues like low levels or contamination.

6. How do I diagnose a P0843 code in a 2017 GMC Sierra?

Diagnosis typically involves using an OBDII scanner to confirm the code, visually inspecting the wiring and connectors, testing the sensor's voltage with a multimeter, and checking transmission fluid levels.

7. Can low transmission fluid cause a P0843 code?

Yes, low or contaminated transmission fluid can cause incorrect pressure readings, which may trigger the P0843 code.

8. How much does it cost to repair a P0843 code on a GMC Sierra?

The cost can vary, but replacing a transmission fluid pressure sensor typically ranges from $150 to $400, including parts and labor. Wiring repairs may cost less depending on the issue.

9. Does a faulty transmission fluid pressure sensor always cause a P0843 code?

Not always. While the sensor is a common culprit, other factors like wiring issues, connector damage, or transmission fluid problems can also cause the code.

10. Will clearing the P0843 code fix the problem on my GMC Sierra?

Clearing the code may temporarily remove the check engine light, but it wonâ€™t resolve the underlying issue. Proper diagnosis and repair are necessary to prevent the code from returning.