P2B79

Coolant Heater B Control Circuit Performance

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$28–89 (est.)

Symptoms

Extended engine warm-up time
Less efficient interior heating
Check Engine Light Illuminates
Possible errors in related systems
Reduced coolant temperature in cold weather

Causes

Coolant heater malfunction
Problems in the electrical circuit (open or short circuit)
Faulty relay or fuse
Problems with the control unit
Corrosion of contacts or connectors

How to Fix

Check heater circuit fuses and relays
Inspect the electrical circuit for damage
Check heater resistance
Check connectors and contacts for oxidation
If necessary, replace the coolant heater

Related codes