P2B78

Coolant Heater B Control Circuit High

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$28–89 (est.)

Symptoms

Extended engine warm-up time in cold weather
Check Engine Light Illuminates
Reduced engine efficiency at low temperatures
Possible errors of related systems

Causes

Open or short circuit in the heater circuit
Coolant heater malfunction
Problems with the relay or circuit fuse
Control module malfunction
Corroded contacts or damaged connectors

How to Fix

Check heater circuit fuses and relays
Diagnose the integrity of wiring and connectors
Check the resistance of the heating element
Scan the control module for other errors
If necessary, replace the coolant heater

Related codes

P2B77 P2B79 P2B80