What Does It Mean?
This generic powertrain diagnostic trouble code (DTC) generally applies to all OBD-II equipped vehicles with a charge air cooler. This may include, but is not limited to, vehicles from Ford, Chevy, Mazda, Toyota, etc.
In forced induction systems, they use a charge air cooler or what I’ll call an intercooler (IC) to help cool the charge air used by the engine. These operate similarly to a radiator.
In the case of the IC, instead of cooling antifreeze, it cools the air to produce a more efficient air/fuel mixture, which in turn leads to better fuel economy, improved performance, etc. In some of these systems, the IC uses a combination of air and coolant to assist in cooling the forced charge air entering the cylinders via forced induction (supercharger or turbocharger).
In these cases, to meet additional coolant flow demands, a coolant pump is used. Generally, these are electric fluid pumps that essentially provide the necessary coolant flow to the IC that the water pump cannot provide independently.
The MIL (Malfunction Indicator Lamp) illuminates on the instrument cluster with P023B and related codes when it monitors a condition outside a specific range in the IC coolant pump control circuit. Off the top of my head, I can think of two causes: one is an obstruction in the pump’s openings causing an electrical value out of range. The other is a rubbed control wire that has severed the electrical connection, causing an open circuit. The point is that both mechanical and electrical faults are possible.
Code P023B, the Charge Air Cooler Coolant Pump Control Circuit Low, is active when there is a low electrical value in the charge air cooler coolant pump and/or its circuit.
How severe is this DTC?
The severity in this case would be low. In most instances, this fault will not present any immediate safety issues. That said, vehicle drivability and performance may suffer, especially if left unaddressed for long enough.
What are some of the symptoms of the code?
Symptoms of a P023B engine code may include:
MIL (Malfunction Indicator Lamp) illuminated
Poor engine performance
Poor fuel economy
Irregular/abnormal engine temperatures
What are some common causes of the code?
Potential causes may include:
Internal mechanical obstruction in the coolant pump
Coolant pump wiring harness broken or damaged
ECM (Engine Control Module) issue
Pin/connector problem (e.g., corrosion, broken locking tab, etc.)
What are the troubleshooting steps for P023B?
Be sure to check Technical Service Bulletins (TSBs) for your vehicle. Accessing a known fix can save you time and money during diagnosis.
Basic Step #1
You first need to locate your IC (Intercooler, AKA Charge Air Cooler). Generally, these are located where they can receive optimal airflow (e.g., in front of the radiator, inside the front bumper, under the hood). Once located, you’ll need to find the coolant lines/pipes to trace back to the coolant pump. It might be tricky to find as they are typically installed in-line with the coolant flow, so keep that in mind. Given the temperatures the cooling system is exposed to, it would be wise to carefully inspect the harness around the area for signs of melting or similar issues.
NOTE: Make sure to let the engine cool down before testing or repairing the cooling system.
Basic Step #2
Check the integrity of your cooling system. Check your coolant levels and also the health of the coolant. Ensure it is clean and full before proceeding.
NOTE: Refer to your service manual to check which specific antifreeze is used for your particular make and model.
Basic Tip #3
Measure and record the integrity of the charge air cooler control circuit. Equipped with a multimeter and the appropriate wiring diagram, you may be able to independently test the control circuit. This might involve disconnecting the connector at the ECM (Engine Control Module) and the other end at the coolant pump. Refer to your wiring diagram for specific wire colors and testing procedures.
NOTE: Ensure the battery is disconnected before performing any electrical repairs.
Basic Step #4
You might be able to independently test the coolant pump depending on your specific system. After all, they are just electric pumps. Refer to the service manual before proceeding, as this might not apply to you. Equipped with a 12-volt power source and a good ground, you can remove the coolant pump from the vehicle (this may involve draining the system) and power it up to see if it activates at all. If it does, you may want to ensure it can also transfer fluid (for reference, these pumps aren’t meant to have a huge amount of pressure or flow, so just inspect the general operation here).
Basic Step #5
ECM diagnosis is always a last resort, but sometimes it can be done with relative ease. This typically involves performing a pin test at the ECM itself and comparing your readings to the desired values. I must emphasize that all other diagnostic strategies should be exhausted beforehand.