What does it mean?
This generic powertrain diagnostic trouble code (DTC) generally applies to all OBD-II equipped vehicles with a supercharger air cooler. This may include, but is not limited to, vehicles from Ford, Chevy, Mazda, Toyota, etc.
In forced induction systems, they use a supercharger air cooler or what I will call an intercooler (IC) to help cool the boosted air used by the engine. These operate similarly to a radiator.
In the case of the intercooler, 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. The intercooler is part of the boost pressure side of the induction system. The bypass valve is used, as its name suggests, to allow air to bypass the intercooler to be vented to the atmosphere and/or recirculated.
The Engine Control Module (ECM) uses it to adjust the valve based on current engine conditions and needs. The ECM also monitors the physical position of the valve using a supercharger air cooler bypass position sensor.
The ECM illuminates the Check Engine Light with P024D and related codes when it detects a condition outside a specified range in the intercooler bypass control circuit and/or in the involved sensors. This code can be triggered by a mechanical and/or electrical fault. If I had to guess here, I would lean towards a mechanical issue likely being the problem. That said, either is possible.
P024D Supercharger Air Cooler Bypass Valve Position Sensor Circuit Range/Performance code is set when there is an out-of-range operating condition in the position sensor or its circuit.
How severe is this DTC?
The severity in this case would be moderate. You don’t want to leave this issue unattended as it could develop into something much more serious quite quickly. Keep in mind that problems do not improve over time unless fixed. Engine damage is expensive, almost every time, so if you have exhausted your abilities, take the vehicle to a reputable repair center.
What are some of the symptoms of the code?
Symptoms of a P024D engine code may include:
Poor engine performance
Vehicle entering “limp mode”
Engine misfire
Poor fuel consumption
What are some common causes of the code?
Causes
of this code may include:
Bypass valve stuck open/closed
Obstruction in the operational movement range of the bypass valve
Faulty supercharger air cooler bypass position sensor
Broken or damaged wiring harness
Faulty fuse/relay
ECM problem
Pin/connector issue (e.g., corrosion, broken locking tab, etc.)
What are the troubleshooting steps for P024D?
Be sure to check Technical Service Bulletins (TSBs) for your vehicle. Access to a known fix can save you time and money during diagnosis.
Basic Step #1
Locate your supercharger air cooler bypass control valve by following the charge piping going to your intercooler (IC); it may be mounted directly on the charge pipe. Depending on your specific make and model, you might find your IC mounted in your front bumper, front fenders, or perhaps directly under the hood among many other possible locations. Once the valve is located, inspect for any obvious physical damage.
NOTE: Ensure the engine is off.
Basic Step #2
It may be straightforward to remove the valve completely from the vehicle to check its functionality. Especially recommended if code P024B is active. Once removed, inspect for any obstruction in the valve’s range of movement. If possible, clean the valve before reinstalling it.
NOTE: Always refer to the service manual first, as this may not be possible or recommended on your specific vehicle.
Basic Tip #3
The bypass valve harness may be routed through areas exposed to the elements. These areas should be closely inspected for nicks, cuts, signs of corrosion, etc., in the wires involved in the circuit.
NOTE: Ensure the battery is disconnected before performing any electrical repairs.
Basic Step #4
Depending on your scan tool, you can check the valve’s functionality by commanding it and observing its range of movement. If accessible, you can disconnect one end of the valve to see the moving parts. Using your scan tool, fully open and close the valve while observing the mechanical operation of the valve itself. If you notice the valve sticking and nothing is obstructing it, the valve is likely faulty. In this case, you can try replacing it. Ensure the manufacturer also recommends a new valve in this scenario. Refer to the manual.
The charge air cooler bypass control sensor is typically located/mounted on the valve itself, in line with the valve’s “door” to effectively monitor its position. It is very important to ensure the “door” is free from any obstruction throughout its entire range of movement.
Basic Step #5
You will want to rule out any electrical issues in the involved harness. To do this, you may need to disconnect it at both the valve and the ECM. Using your multimeter, check the circuit’s integrity by performing many basic electrical tests (e.g., continuity). If everything checks out, there may be input tests you could perform involving testing the connector at the valve to verify ECM functionality with the valve.