Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer has detected a problem with the sensor that measures the electricity going to the heater for the air conditioning system.
This code indicates an issue with the current sensor that monitors the electrical current in the A/C coolant heater's Phase U. The sensor is not reading within the expected range.
The P1D4A code is triggered when the powertrain control module (PCM) detects a range or performance issue with the current sensor for Phase U of the A/C coolant heater. This sensor is responsible for monitoring the electrical current to ensure it is within the specified parameters.
• Check Engine Light is on
• A/C system not functioning properly
• Possible reduction in heating efficiency
• Faulty current sensor
• Wiring issues or poor connections
• Malfunctioning A/C coolant heater
PCM: Powertrain Control Module
A/C: Air Conditioning
• Use an OBD-II scanner to confirm the code
• Inspect the wiring and connections to the current sensor
• Test the current sensor for proper operation
• Replace the faulty current sensor
• Repair or replace damaged wiring or connectors
• Replace the A/C coolant heater if necessary
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Honda Accord
• Honda Civic
• Acura MDX
• Regularly inspect electrical connections
• Ensure proper maintenance of the A/C system
• Use quality replacement parts
Sensor Issue
• Address the issue promptly to avoid further damage
• Consult with a professional mechanic if unsure
Check your vehicle's warranty; sensor issues may be covered under emissions warranty.
This code is relatively uncommon and typically associated with specific models equipped with advanced A/C systems.
Moderate – While the vehicle may still be drivable, the A/C system's performance could be compromised.
Ignoring this issue may lead to further A/C system damage and reduced vehicle comfort.
• Vehicle at operating temperature
• A/C system activated
The current sensor is typically located near the A/C coolant heater, often in the engine compartment.
Q: Can I drive with this code?
A: Yes, but the A/C system may not work properly, affecting comfort.
Q: Is this a common issue?
A: It's not very common and usually occurs in specific vehicle models.
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.