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 a sensor that checks the temperature of a part of the car's motor is saying it's way too cold, which doesn't make sense.
The vehicle's computer has detected that the temperature reading from the Drive Motor 'A' Temperature Sensor 'B' is lower than expected, indicating a possible sensor fault or wiring issue.
The P1B78 code is triggered when the powertrain control module (PCM) receives a signal from the Drive Motor 'A' Temperature Sensor 'B' that indicates an implausibly low temperature. This could be due to a malfunctioning sensor, poor electrical connections, or a fault in the wiring harness.
• Check Engine Light illuminated
• Potential reduction in vehicle performance
• Unusual motor behavior
• Faulty Drive Motor 'A' Temperature Sensor 'B'
• Poor electrical connection
• Damaged wiring harness
PCM: Powertrain Control Module
OBD-II: On-Board Diagnostics II
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors of the temperature sensor.
• Test the temperature sensor for proper operation.
• Replace the Drive Motor 'A' Temperature Sensor 'B'.
• Repair or replace damaged wiring or connectors.
• Clear the code and test drive the vehicle to ensure the issue is resolved.
• OBD-II scanner
• Multimeter
• Basic hand tools
$100 - $300
Moderate
• Chevrolet Volt
• Nissan Leaf
• Toyota Prius
• Regular maintenance checks
• Inspect wiring and connectors periodically
• Ensure sensors are clean and functional
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if unsure.
• Avoid driving the vehicle aggressively until the issue is resolved.
Check with the vehicle manufacturer for specific warranty coverage on sensors.
This code has been reported in hybrid and electric vehicles where temperature sensors play a critical role in motor management.
Moderate – It is advisable to address this issue soon to prevent potential motor performance issues.
Driving with a malfunctioning temperature sensor can lead to further vehicle damage. Ensure repairs are conducted by a qualified technician.
• Vehicle at operating temperature
• Sensor and wiring visually inspected
The Drive Motor 'A' Temperature Sensor 'B' is typically located near the drive motor assembly.
Q: Can I drive my car with this code?
A: It's best to have it checked as soon as possible to avoid potential damage.
Q: Will this issue affect my car's performance?
A: It might, as incorrect temperature readings can affect motor operations.
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