P023C High Boost Air Cooler Coolant Pump Control Circuit

Meaning of Code P023C

This generic OBD-II code applies to vehicles equipped with a charge air cooler (intercooler). It indicates an abnormally high electrical value in the control circuit of the coolant pump associated with the cooler. This system cools the air compressed by the turbocharger or compressor to optimize engine performance.

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Severity

Low level:

• No immediate safety risk.

• Possible impact on performance, fuel consumption, or engine temperature if unresolved.

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Common Symptoms

• Check engine light on (MIL).

• Loss of power or sluggish acceleration response.

• Increased fuel consumption.

• Unstable or abnormal engine temperatures.

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Possible Causes

1. Mechanical obstruction in the coolant pump.

2. Electrical issues:

   • Damaged, chafed, or cut wiring harness.

   • Corroded, oxidized, or improperly connected connector.

3. Pump failure (electric motor burnt out).

4. ECM failure (rare, check last).

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Troubleshooting Procedure

Step 1: Check Technical Service Bulletins (TSB)

• Verify if the manufacturer has released any fixes for this code on your model.

Step 2: Locate and Inspect the Cooler and Pump

1. Locate the intercooler: Typically near the radiator or front bumper.

2. Inspect coolant lines:

   • Look for leaks, cracks, or corrosion deposits.

   • Check coolant level and quality (refer to the manual for the specific type).

⚠️ Precautions:

• Work on a cold engine to avoid burns.

• Disconnect the battery before any electrical work.

Step 3: Test the Electrical Circuit

1. Check wiring and connectors:

   • Look for chafed wires, melted insulation, or oxidized pins.

   • Clean connectors with contact cleaner spray and apply dielectric grease.

2. Measure continuity and resistance:

   • Use a multimeter to check for no short circuits or open circuits.

   • Compare values with manufacturer specifications.

Step 4: Test the Coolant Pump

1. Direct power supply:

   • Remove the pump (drain the circuit if necessary).

   • Power it with 12V (external source) to verify operation.

   • Ensure it generates minimum flow (even if weak).

2. Mechanical inspection:

   • Check for obstructions (debris, deposits) in the inlet/outlet ports.

Step 5: ECM Diagnosis

• Measure ECM output signals to the pump using an oscilloscope or diagnostic tool.

• If in doubt, consult a professional for ECM reprogramming or replacement.

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Recommended Solutions

• Replace the pump if faulty (average cost: €100 to €300).

• Repair the wiring harness: Replace damaged sections and secure fastenings.

• Clean the cooling circuit if contaminated.

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Final Precautions

• Reset the code after repair and test the vehicle over several driving cycles.

• Use original parts to ensure electrical and mechanical compatibility.