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 part of the car that controls the heating and cooling system is not working right. It's like when a remote control doesn't change the TV channel because it's not sending the right signal.
The P1D98 code indicates that the control circuit for the heat pump expansion valve 'C' has a higher than expected voltage or resistance, suggesting an electrical issue.
The heat pump expansion valve 'C' is part of the vehicle's climate control system. It regulates the flow of refrigerant to adjust the temperature inside the vehicle. A 'control circuit high' condition means the electrical circuit is reading a higher voltage than normal, which could be due to a short circuit, faulty wiring, or a defective valve.
• Air conditioning not cooling properly
• Unusual noises from the climate control system
• Warning light on the dashboard
• Faulty heat pump expansion valve 'C'
• Short circuit in the wiring
• Defective control module
OBD-II: On-Board Diagnostics, a standardized system for self-diagnostics in vehicles.
HVAC: Heating, Ventilation, and Air Conditioning, the system that manages climate control in a vehicle.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage.
• Test the expansion valve for proper operation.
• Replace faulty wiring or connectors.
• Replace the heat pump expansion valve 'C'.
• Reprogram or replace the control module if necessary.
• OBD-II scanner
• Multimeter
• Screwdriver set
$200 - $600
Moderate
• Honda Accord Hybrid
• Toyota Prius
• Chevrolet Volt
• Regular maintenance checks on the climate control system.
• Ensure proper electrical connections.
• Avoid overloading the vehicle's electrical system.
Sensor Issue
• Have the vehicle inspected by a professional mechanic.
• Avoid using the climate control system until repaired to prevent further damage.
Check with the vehicle manufacturer for warranty coverage on climate control components.
This code is relatively uncommon and typically associated with hybrid or electric vehicles with advanced climate control systems.
Moderate – While not immediately dangerous, it can lead to discomfort and further issues if left unaddressed.
Ensure repairs are conducted by a certified technician to maintain vehicle safety and compliance with regulations.
• Vehicle at operating temperature
• Climate control system activated
The heat pump expansion valve 'C' is typically located near the vehicle's HVAC unit, often behind the dashboard.
Q: Can I drive my car with this code?
A: Yes, but it is recommended to get it checked soon to avoid discomfort or further damage.
Q: Will this code affect my car's performance?
A: It primarily affects the climate control system, not the engine performance.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
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.
View on Amazon
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.