AutoCodes – GMC – P0843 2015 GMC Sierra

P0843 2015 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 2015 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 206

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 2015 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 2015 GMC Sierra - Transmission Fluid Pressure Switch 1 Circuit High Voltage - AutoCodes.com — P0843 2015 GMC Sierra Code - Transmission Fluid Pressure Switch 1 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0843 2015 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 2015 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 2015 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 2015 GMC Sierra 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 2015 GMC Sierra Code

1. What does the OBDII code P0843 mean on a 2015 GMC Sierra?

P0843 indicates "Transmission Fluid Pressure Switch 1 Circuit High Voltage," which means the powertrain control module (PCM) has detected an abnormally high voltage signal from the transmission fluid pressure switch.

2. What are the common symptoms of code P0843 on a 2015 GMC Sierra?

Symptoms may include erratic shifting, the transmission being stuck in one gear, failure to engage certain gears, reduced fuel efficiency, and the check engine light being illuminated.

3. What causes P0843 on a 2015 GMC Sierra?

Common causes include a faulty transmission fluid pressure sensor, damaged or corroded wiring or connectors, a malfunctioning PCM, or low or contaminated transmission fluid.

4. Can driving with code P0843 damage my 2015 GMC Sierra?

Yes, driving with this code can cause further damage to the transmission due to improper fluid pressure regulation and erratic shifting. It's best to address the issue promptly.

5. How do I diagnose code P0843 on a 2015 GMC Sierra?

Start by inspecting the transmission fluid level and condition, checking the wiring and connectors for damage or corrosion, and testing the transmission fluid pressure sensor for proper operation.

6. Can low transmission fluid cause P0843 on a 2015 GMC Sierra?

Yes, low or contaminated transmission fluid can lead to abnormal pressure readings, triggering the P0843 code.

7. How do I fix code P0843 on a 2015 GMC Sierra?

Repairs may include replacing a faulty transmission fluid pressure sensor, repairing or replacing damaged wiring or connectors, or performing a transmission fluid flush and refill.

8. How much does it cost to fix code P0843 on a 2015 GMC Sierra?

Repair costs vary, but replacing a transmission fluid pressure sensor typically costs between $150 and $300, including labor. Additional repairs may increase the cost.

9. Can a faulty PCM cause code P0843 on a 2015 GMC Sierra?

While less common, a malfunctioning PCM could cause the code if it sends or interprets incorrect voltage signals from the pressure sensor.

10. Do I need to reprogram the PCM after fixing code P0843 on a 2015 GMC Sierra?

In most cases, reprogramming the PCM is unnecessary. However, clearing the code with a scan tool and performing a test drive to ensure the issue is resolved is recommended.