P023B Code: Charge-Air Cooler Pump A Circuit Low
P023B: Prove the Pump Circuit
Keep an electrical-low fault separate from coolant flow and pump performance.
DIAGNOSTIC FOCUS
- FAULT TYPE
- Charge-air cooler pump A control
- FIRST CHECKS
- Power, control, load and connector integrity
Pump A location, direct or module control, coolant circuit and enable conditions vary by engine and electrified-powertrain design.
P023B means Charge Air Cooler Coolant Pump A Control Circuit Low. The controller monitored the charge-air cooler coolant pump A control path at a low electrical state when another state was expected. This is not direct proof of low coolant flow, a failed pump motor or an overheated charge-air cooler.
Save the complete fault event before clearing it: pump command and feedback, charge-air/coolant temperatures, system voltage, engine load, related U02A9 communication or P023A/P023C circuit faults and thermal warnings. Map the exact pump and controller, load-test power and ground, inspect the known high-risk connector/routing areas, and separate circuit integrity from coolant-loop performance.
What Does the P023B Code Mean?
Water-cooled charge-air systems circulate coolant through a low-temperature radiator, reservoir and intercooler core. A dedicated electric pump may be powered directly by a relay, driven by a controller or contain its own electronics and network interface.
Circuit low means the monitored control electrical state fell below the strategy's expected state. A short to ground, poor power feed, connector fault, overloaded pump or failed driver can create it; a blocked hose or air pocket is a separate hydraulic concern.
Some vehicles combine P023B with pump-communication or thermal faults. Always identify whether the code refers to an external control wire, internal electronics or a smart pump module before testing.
Save requested pump state, available speed/current/feedback and the temperatures that caused the command.
Measure power and ground while the pump is commanded, not only with the connector unplugged.
A correct circuit does not prove flow; a blocked or air-locked loop needs a separate coolant-circuit test.
P023B Symptoms, Severity, and Driving Safety
The controller may detect the circuit before the driver notices charge-temperature effects.
Thermal protection may limit torque when charge cooling is unavailable. Confirm command and temperature data.
Temperature can rise under load, but sensor faults and airflow restrictions require separate evidence.
Silence is a clue only when the pump should be commanded. Some strategies do not run it continuously.
Vibration, terminal push-out or moisture can interrupt a low-current control or smart-pump connection.
A leak can impair cooling but does not by itself prove a circuit-low code. Stop for significant coolant loss.
Prompt diagnosis matters because charge-air cooling protects performance and, on some electrified vehicles, shares thermal management with sensitive components. Stop for overheating, major coolant loss, reduced-power warnings or a high-voltage thermal warning.
P023B Causes: Low Control Path, Pump Load, or Module?
Trace the control path under load, then verify the coolant loop separately. Pump replacement is justified only after feed, ground, command and connector evidence identify an internal load or electronics fault.
Control Circuit Shorted to Ground
Chafing or moisture can hold an external control or feedback line low.
How to prove it: Isolate harness sections with the OEM diagram while monitoring command and feedback.
Check firstWeak Power Feed or Excessive Voltage Drop
A fuse, relay, connector or supply splice may deliver voltage unloaded but collapse under pump current.
How to prove it: Command the pump safely and measure loaded voltage at the exact feed and ground points.
Check firstPoor Ground or Terminal Contact
Corrosion, terminal push-out or loose fit can limit current or communication.
How to prove it: Inspect retention and voltage drop; a Stellantis case specifically documents a pushed-out terminal on a covered application.
Verify directlySeized or Overloaded Pump Motor
Mechanical drag or internal electronics can pull the control state low or cause protection.
How to prove it: Compare current, command and rotation/feedback with the OEM method before replacing the pump.
Verify directlyController or Smart-Pump Communication Fault
An integrated pump may need wake-up, network and internal-driver checks rather than a simple relay test.
How to prove it: Read all modules and verify powers, grounds and communication before module replacement.
Verify directlyCoolant-Loop Restriction or Air Pocket
A separate hydraulic fault can coexist and cause poor cooling after the electrical code is repaired.
How to prove it: Bleed by the published method and prove flow/temperature change without calling it the cause of circuit low unless evidence links them.
Final branchDo not use a universal voltage, duty cycle or current limit. Pump architecture and driver diagnostics differ widely, especially between conventional and electrified vehicles.
Using UR800 to Organize P023B Evidence
The iCARZONE UR800 Full-System Bidirectional Scan Tool with ECU Coding supports full-system diagnostics, available DTCs, freeze frame, ECU information and live data. Save full-system faults, pump command, available duty/speed/current/feedback, charge-air and coolant temperatures, system voltage and related communication faults. A supported output test can show whether command produces electrical and thermal response.
The official product page advertises bidirectional control and ECU coding. Coverage varies by VIN, ECU and software. An active test may be conditional and cannot prove terminal tension, actual coolant flow, pump impeller condition or safe high-voltage isolation. Confirm function coverage by VIN.
Use the wiring diagram, fused/load-safe electrical tests, current measurement and the published cooling-system fill/bleed or flow procedure. Never open a hot system or improvise power at a smart pump.
iCARZONE UR800 Full-System Bidirectional Scan Tool with ECU Coding
Compare supported pump command and feedback with charge-air temperature while preserving related thermal and network faults.
Price and availability checked September 2, 2026. Prices shown are USD. Recheck the current offer, stock and required vehicle/function coverage before purchase.
How to Diagnose P023B From Command to Pump Current
P023B requires two linked but distinct proofs: why the monitored circuit is low, and whether the repaired pump moves coolant correctly. Start with stored command/feedback evidence and loaded electrical tests.
P023B Quick Diagnostic Path
-
1
Preserve the Thermal and Electrical Event
- Save P023B status, freeze frame, every thermal/network fault and exact warning before clearing.
- Record pump command/feedback, system voltage, charge-air temperature, relevant coolant temperatures and engine/propulsion load.
-
2
Identify Pump A and the Control Architecture
- Use VIN diagrams to locate pump A, its coolant circuit, fuse/relay or controller, connector and any network connection.
- Confirm whether the pump is conventional, PWM-controlled or smart before applying any test voltage.
-
3
Inspect Cold and Check Shared Conditions
- With the system cold, verify coolant level by the approved method and inspect for leaks, connector damage and harness routing.
- Prioritize shared power, ground or communication faults when multiple cooling devices are affected.
-
4
Load-Test the Electrical Path
- Command the pump only when safe and measure feed/ground voltage drop, control state and current under load.
- Protect the driver and do not pierce sealed wiring without an approved repair plan.
-
5
Separate Internal Pump and Coolant-Loop Faults
- If power/control are correct, evaluate current, speed/feedback and pump operation; then assess air, restriction and flow separately.
- Follow the exact fill/bleed procedure. An air pocket can imitate poor cooling after a valid electrical repair.
-
6
Repair and Verify Thermal Control
- Repair the proven terminal, harness, supply, ground, pump or controller issue and correct any verified coolant leak/restriction.
- Confirm pump command and feedback, stable current, expected temperature response and no returning P023B or companion thermal faults under controlled load.
How to Fix P023B and Verify the Repair
Repair a Proven Harness or Terminal Fault
Restore sealed wiring, terminal retention and routing where the loaded circuit test fails.
Restore Power, Ground, or Control
Correct a demonstrated fuse, relay, splice, ground or controller output issue.
Replace a Proven Pump Assembly
Use loaded voltage, current and feedback/rotation evidence to justify the exact pump.
Bleed or Repair the Coolant Loop
After electrical repair, correct proven leaks, trapped air or restriction using the specified coolant and procedure.
Electrical and Thermal Data Diagnosis
VIN-specific quoteCommand/feedback graphing and loaded circuit tests establish scope.
Connector or Harness Repair
VIN-specific quoteSealing, terminal access and routing determine labor.
Pump Replacement and Coolant Service
VIN-specific quotePump location, integrated electronics and coolant handling affect the estimate.
Bleed and Load Verification
VIN-specific quoteVacuum fill or automated bleed plus thermal testing should be itemized.
Ask for separate electrical diagnosis, pump part, coolant service and bleed/verification lines. P023B alone cannot justify replacing a pump and radiator together.
Verification should include both correct electrical state and a controlled temperature/flow response at the conditions that require pump operation.
P023B Cooling Architectures, Thermal Risk, and DIY Limits
A Stellantis STAR case documents P023B with U02A9 on a listed application and instructs inspection of a specific pump connector for a pushed-out terminal. It is an example, not a universal connector location.
Circuit tests differ if electronics and network communication are inside the pump.
One OEM case identifies terminal push-out; verify VIN and connector identity before applying it.
Electrical repair must be followed by coolant level, bleed and temperature-response verification.
A VW Touareg quick-reference book defines P023B as charge-air cooler coolant pump control circuit low and publishes application-specific electrical criteria, demonstrating why generic thresholds should not be reused.
- Save codes, commands and temperature data.
- Inspect cold coolant level and visible leaks.
- Check safely accessible connectors and fuses.
- Stop for overheating or major coolant loss.
- Power a smart pump or back-probe a driver.
- Open a hot/pressurized cooling circuit.
- Enter high-voltage thermal components.
- Bleed and load-test without OEM procedure.
Frequently Asked Questions About P023B
What does P023B mean?
Is the coolant pump definitely bad?
Can low coolant cause P023B?
What is pump A?
Can I power the pump with battery voltage?
Can the vehicle be driven?
Can UR800 test the pump?
How is the repair verified?
Sources and Technical Review Notes
- Stellantis STAR Case S2108000088 — Defines P023B and documents one application-specific pump-connector terminal inspection.
- VW Touareg Quick Reference Specification Book — Lists P023B and application-specific circuit criteria, supporting circuit-low and OEM-threshold limits.
- Stellantis TSB 23-019-25 Rev. A — Lists P023B among codes on a narrowly defined vehicle campaign, showing VIN/build applicability matters.
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