P0843 2018 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 2018 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.
Code P0843 2018 GMC Sierra Description
What are the Possible Causes of the DTC P0843 2018 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 2018 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 2018 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.
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Frequently Asked Questions about P0843 2018 GMC Sierra Code
1. What does the OBDII code P0843 mean on a 2018 GMC Sierra?
The P0843 code indicates a "Transmission Fluid Pressure Switch 1 Circuit High Voltage," meaning the transmission control module (TCM) is detecting an unusually high voltage from the pressure switch 1 circuit.
2. What are the common symptoms of a P0843 code on a 2018 GMC Sierra?
Common symptoms include harsh or delayed shifting, transmission slipping, the vehicle entering limp mode, or the illumination of the check engine light.
3. What causes the P0843 code on a 2018 GMC Sierra?
Possible causes include a faulty transmission fluid pressure switch, damaged wiring or connectors in the switch circuit, low or dirty transmission fluid, or a malfunctioning transmission control module (TCM).
4. Can low transmission fluid cause the P0843 code?
Yes, low or dirty transmission fluid can cause abnormal pressure readings, potentially triggering the P0843 code.
5. How do you diagnose the P0843 code on a 2018 GMC Sierra?
Diagnosis involves checking the transmission fluid level and condition, inspecting the wiring and connectors for damage, testing the pressure switch for proper operation, and using a scan tool to monitor voltage readings from the circuit.
6. Can I drive with the P0843 code on my 2018 GMC Sierra?
It’s not recommended to drive for extended periods, as this code may indicate transmission issues that could worsen and lead to more severe damage or unsafe driving conditions.
7. How is the P0843 code fixed on a 2018 GMC Sierra?
Repairs may include replacing the faulty pressure switch, repairing or replacing damaged wiring or connectors, flushing and refilling the transmission fluid, or reprogramming or replacing the TCM if necessary.
8. How much does it cost to fix the P0843 code on a 2018 GMC Sierra?
Repair costs vary but may range from $150 to $400, depending on whether the issue is with the pressure switch, wiring, or other components.
9. Can a software update fix the P0843 code on a 2018 GMC Sierra?
In some cases, a transmission control module (TCM) software update may resolve the issue if it’s related to incorrect voltage readings or a software glitch.
10. What tools are needed to troubleshoot the P0843 code on a 2018 GMC Sierra?
You’ll need an OBDII scan tool, a multimeter for voltage testing, and potentially a transmission pressure gauge for further diagnosis.
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