P0843 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 1 Circuit High Voltage
Quick Answer
The P0843 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates that the transmission fluid pressure switch 1 circuit is registering a high voltage. Common causes include Faulty transmission fluid pressure switch, Wiring or electrical issues in the circuit, Low transmission fluid levels. 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 Faulty transmission fluid pressure switch, Wiring or electrical issues in the circuit, Low transmission fluid levels.
- 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 P0843 2018 GMC Sierra Description
The P0843 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates that the transmission fluid pressure switch 1 circuit is registering a high voltage. This switch is responsible for monitoring the fluid pressure within the transmission system. When the voltage detected by the switch is higher than expected, it can lead to various issues with the transmission's operation.
Common Causes of P0843 2018 GMC Sierra
- Faulty transmission fluid pressure switch
- Wiring or electrical issues in the circuit
- Low transmission fluid levels
- Contaminated or degraded transmission fluid
- Internal transmission problems
Symptoms of P0843 2018 GMC Sierra
- Erratic shifting or slipping gears
- Limp mode activation
- Delayed engagement when shifting gears
- Transmission overheating
- Illumination of the check engine light
How to Fix P0843 2018 GMC Sierra
- Begin by diagnosing the exact cause of the high voltage reading, which may involve testing the transmission fluid pressure switch and inspecting the wiring and connections.
- If the switch is found to be faulty, it will need to be replaced with a new one. Ensure that the replacement switch is compatible with the specific make and model of the vehicle.
- Check the transmission fluid level and condition. If low or contaminated, perform a fluid flush and refill with the manufacturer-recommended fluid.
- Clear the DTC from the vehicle's computer system using a diagnostic scanner to reset the check engine light and monitor the transmission's operation for any further issues.
- Test drive the vehicle to confirm that the repair has resolved the P0843 code and that the transmission is functioning correctly.
Cost to Fix P0843 2018 GMC Sierra
The typical repair costs for addressing a P0843 code on a 2018 GMC Sierra can vary depending on the specific cause of the issue. In general, replacing the transmission fluid pressure switch and performing any necessary fluid flushes or repairs can range from $200 to $500. Additional costs may apply if there are underlying transmission problems that need to be addressed. It's important to note that labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate.
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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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