Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with the part of the car that helps keep the engine warm. It's like when your blanket doesn't work and you feel cold.
The P2B79 code is triggered when the Engine Control Module (ECM) detects a performance issue in the control circuit of the Coolant Heater B.
The coolant heater is responsible for warming the engine's coolant to help the engine reach its optimal operating temperature quickly. The 'B' circuit refers to a specific part of the heater system. A performance issue indicates that the circuit is not operating within the expected parameters, which could be due to electrical faults or component failures.
• Engine takes longer to warm up
• Check Engine Light is on
• Reduced heater performance in the cabin
• Faulty coolant heater
• Wiring issues in the coolant heater circuit
• Defective control module
ECM: Engine Control Module
OBD-II: On-Board Diagnostics II
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage.
• Test the coolant heater for proper operation.
• Repair or replace damaged wiring.
• Replace the faulty coolant heater.
• Reprogram or replace the control module if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regular maintenance checks
• Ensure coolant levels are adequate
• Inspect wiring for wear and tear
Sensor Issue
• Get the vehicle checked by a professional mechanic.
• Avoid long drives until the issue is resolved.
Check if your vehicle's warranty covers the coolant heater system.
This code is not very common and typically occurs in colder climates where the coolant heater is more frequently used.
Moderate – While the vehicle can still be driven, it may not perform optimally, especially in cold weather.
Ignoring this issue could lead to increased emissions and reduced engine efficiency.
• Engine cold start
• Ambient temperature below normal operating conditions
The coolant heater is typically located near the engine block or integrated into the cooling system.
Q: Can I drive with this code?
A: Yes, but it's best to get it fixed soon to avoid further issues.
Q: Will this affect my car's heating?
A: Yes, it might reduce the effectiveness of the cabin heater.
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