P2CB4: Charge Air Cooler Coolant Pump B Supply Voltage Circuit

What it means

Charge air cooler coolant pump B reports a supply voltage circuit condition. CAC coolant loop circulation is impaired.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

Pump B needs a sound supply circuit to circulate coolant through the charge air cooler loop. This code identifies a fault in the pump B supply-voltage circuit, such as a blown fuse or wiring problem, which can leave the pump without adequate power.

Common causes

Most likely first.

1. Supply fuse blown
2. Wiring or connector fault

Symptoms

• Check-engine light
• Reduced engine power
• Possible charge-air temperature warning

How to diagnose it

1. Record freeze-frame data and check live pump B command and status to establish when the supply fault is detected.
2. With the vehicle safely switched off, inspect the pump B connector and harness for corrosion, loose pins, chafing or heat damage.
3. Check the pump B supply fuse and inspect the circuit for a short or overload if the fuse is blown.
4. Measure supply voltage and ground at pump B while commanded on, comparing results with the manufacturer's specification.
5. Trace any missing or low voltage through the supply wiring and connector points to locate an open, high resistance or short.

Common fixes

• Reconnect and clean the pump B connector if contact is poor.
• Repair chafed, broken or corroded supply wiring or ground connections.
• Replace a blown fuse after correcting the cause of the overload.
• Replace pump B only if its supply circuit is correct and the pump itself fails testing.

Can I keep driving?

Limit driving and avoid heavy acceleration, since pump B may not circulate coolant and engine power may be reduced. Stop if a charge-air temperature warning appears or the vehicle loses significant power.