Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer has detected a problem with the electrical circuit that controls a part of the air conditioning system called the expansion valve. It's like a switch that isn't working right.
The P1D94 code indicates that there is a high voltage issue in the control circuit for the heat pump expansion valve 'B'.
The expansion valve 'B' in the heat pump system is responsible for regulating the flow of refrigerant. A high control circuit signal indicates that there is an issue with the electrical signal being sent to or from the valve, which may be due to a wiring problem, a faulty valve, or an issue with the control module.
• Air conditioning not working properly
• Unusual noises from the HVAC system
• Check engine light illuminated
• Faulty heat pump expansion valve 'B'
• Wiring issues in the control circuit
• Faulty control module
OBD-II: On-Board Diagnostics, a standardized system for self-diagnostics and reporting in vehicles.
HVAC: Heating, Ventilation, and Air Conditioning system in a vehicle.
• Use a scan tool to verify the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the expansion valve 'B' for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the expansion valve 'B' if faulty.
• Replace or reprogram the control module if necessary.
• OBD-II scan tool
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Honda Accord Hybrid
• Toyota Prius
• Chevrolet Volt
• Regular maintenance of the HVAC system
• Inspect wiring and connectors periodically
• Avoid overloading the electrical system
Sensor Issue
• Have the vehicle inspected by a professional if the check engine light is on.
• Avoid using the air conditioning until the issue is resolved.
Check with your vehicle manufacturer for warranty coverage on HVAC components.
This code has been associated with hybrid and electric vehicles that use heat pump systems for climate control.
Moderate – While not immediately critical, it can affect comfort and efficiency.
Driving with a malfunctioning HVAC system may not be illegal, but it can affect comfort and visibility in certain weather conditions.
• Vehicle must be running.
• Air conditioning system should be activated.
The expansion valve 'B' is typically located within the HVAC system, often near the evaporator or condenser.
Q: Can I drive with this code?
A: Yes, but it is recommended to fix it soon to ensure proper air conditioning function.
Q: Will this code affect my car's performance?
A: It primarily affects the HVAC system, not the engine performance.
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Network faults often require full-system access instead of a generic code reader alone.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.
Fitment Required · Vehicle-fitment part
Relevant when EVAP diagnosis points toward purge-flow or purge-control faults.
EVAP diagnosis often includes purge-flow and valve-control faults.
Confirm the failed valve and exact fitment before buying parts.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.