P2601 Code: Coolant Pump A Performance/Stuck Off
P2601: Prove Pump Operation and Coolant Flow
Identify which pump is A, inspect the cold system, then compare command, feedback and thermal response.
DIAGNOSTIC FOCUS
- FAULT TYPE
- Coolant pump A functional performance or stuck-off result
- FIRST CHECKS
- Correct loop, coolant/bleeding, hoses, power/ground, communication, feedback and thermal response
The current label is Performance/Stuck Off. It is separate from P2600 open, P2602 low and P2603 high electrical records.
P2601 means Coolant Pump ‘A’ Control Circuit Performance/Stuck Off. The responsible controller expected the OEM-defined pump to operate, but its feedback, communication, electrical load, temperature profile or resulting coolant flow did not satisfy the functional monitor. This does not identify a universal pump location.
Save cooling, hybrid, voltage and communication evidence before clearing. Let the vehicle cool, identify which circuit and pump the VIN calls A, verify coolant level/type and bleeding, inspect hoses and electrical paths, then compare supported command with feedback and a safe physical or thermal response.
What Does the P2601 Code Mean?
P2601 is currently defined as Coolant Pump ‘A’ Control Circuit Performance/Stuck Off. It is a functional or rationality result: the controller commanded or expected pump operation but did not observe the required current, speed/feedback, communication, coolant-flow or temperature response. It is not direct proof that the pump motor itself failed.
A General Motors certification example monitors the coolant-temperature profile while an auxiliary after-run pump is enabled during hot soak. A 2025 Stellantis hybrid bulletin applies P2601-00 to an auxiliary electric pump with power and LIN communication and tells technicians to inspect coolant level/type, leaks, hoses, fuse, connectors, supply and LIN wiring before replacement. Other vehicles use different feedback and model logic.
The spreadsheet’s Range/Performance wording reflects older or generalized material. The current source wording is Performance/Stuck Off, while older OEM documents may call the functional test rationality or range/performance. That terminology change does not make P2601 equivalent to the neighboring electrical continuity records P2600 open, P2602 low or P2603 high.
Save engine, hybrid, cooling, voltage, communication and temperature-sensor records plus freeze frame and any over-temperature history.
Identify which pump is A, what circuit it cools, how it is powered or addressed, and the exact filling and bleeding procedure.
Compare supported command with pump feedback/current, communication, verified flow and temperature behavior only under the OEM test conditions.
P2601 Symptoms, Severity, and Cooling-System Safety
An engine, coolant, hybrid or reduced-power warning may appear when the monitor fails.
Engine, inverter, turbocharger or auxiliary-loop temperature can climb when that pump is required.
Some applications protect the powertrain or hybrid system when expected cooling is unavailable.
Heater performance can change when the affected pump serves or influences the cabin-heating circuit.
Sound or circulation may be absent or intermittent only where the design normally runs the pump in that state.
A pump used only during certain thermal conditions can set a history code while routine driving still feels normal.
Treat any rising temperature, coolant loss, steam, reduced-power or shutdown warning as urgent. Stop driving, switch the vehicle off when safe, keep clear of the hot pressurized system and arrange service. A stored P2601 with stable temperature still requires prompt diagnosis because the pump may be needed only after shutdown, during boost, for cabin heat or for a hybrid component. The code cannot establish a safe driving distance.
P2601 Causes and the Evidence That Separates Them
Start with the thermal circuit, not the pump catalog. Low or incorrect coolant, trapped air, a leak, kinked hose or poor bleeding can make a healthy pump fail the monitor. Then separate power and communication faults from a mechanically weak or stuck pump. Temperature-sensor plausibility and controller logic matter because some monitors infer flow rather than directly measuring it.
Coolant, Air, Leak, or Flow Restriction
Low or wrong coolant, trapped air, a leak, kinked hose, blockage or incorrect bleeding can prevent the expected circulation and temperature change.
How to prove it: Inspect the fully cool system, pressure-test as specified, verify coolant type and complete the exact fill/bleed procedure.
Check firstPump Mechanical or Electronic Fault
The impeller, motor, internal electronics or feedback can stick, weaken, obstruct or fail.
How to prove it: After coolant and circuit checks, compare supported command with current, feedback and verified flow using the OEM criteria.
Check firstFuse, Feed, Ground, or Connector Fault
A blown fuse, high-resistance supply, poor ground, damaged connector or coolant/water intrusion can leave the pump unable to run.
How to prove it: Load-test the exact supply and ground, inspect sealing and reproduce the command without universal current limits.
Verify directlyLIN, PWM, Relay, or Feedback Path
Pump control can use LIN communication, PWM, a relay or dedicated feedback depending on architecture.
How to prove it: Map the VIN circuit and test the named path with the specified message, waveform and load method.
Verify directlyTemperature or Thermal-Model Input Fault
Incorrect sensor data or another cooling-system condition can invalidate a rationality monitor even when the pump runs.
How to prove it: Compare related temperatures for plausibility and inspect their circuits before concluding that flow is absent.
Verify directlyCalibration or Controller Fault
Software or controller failure remains possible after coolant, plumbing, pump, circuit, communication and sensor checks.
How to prove it: Verify applicable bulletins and complete controller power, ground and isolation tests before programming or replacement.
Final branchDo not import another vehicle’s temperature gradient, current, PWM, LIN or voltage threshold. GM and Stellantis examples use different pump roles and monitor methods; the exact test belongs to the VIN and installed calibration.
Using UR1000 to Organize P2601 Evidence
The iCARZONE UR1000 Bidirectional Scan Tool with ECU Coding supports full-system diagnostics, available DTCs, freeze frame, ECU information and live data. Save P2601 status, freeze frame, failure order and all cooling, hybrid, voltage, communication and temperature-sensor codes. Record supported pump command, duty or state, feedback/speed/current, relevant coolant temperatures and fan operation before clearing. Mark whether the failure occurred running, after shutdown or in another thermal state.
The official product page advertises bidirectional control and ECU coding. Coverage varies by VIN, ECU and software. A scan tool can organize command and feedback data, but it cannot prove coolant type, air pockets, hose restriction, impeller condition or actual flow without physical evidence. The exact pump command and active test may be unavailable on a given VIN, ECU or software version; unsupported coverage does not prove a fault.
Work only after full cool-down using the VIN cooling diagram, specified coolant, approved fill/bleed and pressure-test equipment, a capable multimeter and the exact electrical or communication procedure. Follow high-voltage isolation where the loop is near electrified components. Keep hands and leads clear because pumps and fans can start automatically.
iCARZONE UR1000 Bidirectional Scan Tool with ECU Coding
Save the complete P2601 thermal event and compare supported pump command, feedback, temperature, voltage and communication data before clearing.
Price and availability checked September 3, 2026. Prices shown are USD. Recheck the current offer, stock and required vehicle/function coverage before purchase.
How to Diagnose P2601 in 6 Evidence-Based Steps
Diagnose P2601 with the vehicle fully cool and the correct pump identified. Preserve the thermal event, verify coolant condition and plumbing, then prove electrical control and the resulting flow or temperature response. Do not command a pump or open the system until the OEM safety and bleeding requirements are understood.
P2601 Quick Diagnostic Path
-
1
Preserve the Cooling-System Record
- Save engine, hybrid, cooling, voltage and communication codes plus freeze frame, pump data, relevant temperatures and any over-temperature event.
- Boundary: Do not clear evidence or continue testing through an active over-temperature condition.
-
2
Identify Pump A and Its Loop
- After full cool-down, use VIN information to identify the pump, served circuit, control type, coolant specification, bleeding method and applicable bulletins.
- Boundary: Pump A is not universally the main water pump or in one standard location.
-
3
Inspect Coolant, Plumbing, and Hardware
- Check level/type, leaks, hoses, reservoir, clamps, fuse/relay if fitted, connector, harness, powers and grounds for restriction, air entry, corrosion and damage.
- Boundary: Never open a hot pressurized cap; electric pumps and fans can start with the engine off.
-
4
Test Power, Ground, and Control
- Use the OEM pinout and load method to test supply, ground voltage drop, LIN/PWM/relay command, feedback and controller powers.
- Boundary: Do not apply universal resistance, current, duty-cycle, LIN or voltage limits.
-
5
Compare Command with Flow and Temperature
- If supported for the exact VIN, command the pump and compare feedback/speed/current, verified circulation and temperature trends after correct bleeding.
- Boundary: An unsupported active test is a coverage limit; do not substitute an improvised jumper or run a hybrid loop without required isolation.
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6
Repair, Refill, Bleed, and Verify
- Repair the proven coolant, plumbing, circuit, communication, sensor, software or pump fault, then refill and bleed exactly and complete the thermal or after-run confirmation.
- Boundary: Verify stable temperatures, correct pump response, no leaks and no returning current or pending P2601.
How to Fix P2601 and Verify Coolant Circulation
Correct Coolant, Leaks, Restriction, or Air
Use the specified coolant, repair the proven plumbing fault and complete the exact vacuum-fill or bleed process.
Restore Power, Ground, or Communication
Repair sealed terminals, fuse/feed, ground, LIN/PWM/relay or feedback integrity where the specified test fails.
Replace a Proven Pump or Sensor
Use the VIN-correct component only after command-to-response or plausibility testing isolates it.
Complete an Eligible Software or Controller Action
Confirm bulletin applicability, power/ground integrity and programming authorization before service.
Cooling and Electrical Diagnosis
VIN-specific quoteFull scan, cooling diagram, cold inspection, loaded circuit test and command-to-response measurement should be itemized.
Coolant, Hose, Connector, or Harness Repair
VIN-specific quoteAccess, contamination, refill method, terminals and leak source determine labor and materials.
Pump or Sensor Replacement
VIN-specific quotePump location, loop type, high-voltage proximity, coolant quantity and required bleeding vary by VIN.
Thermal-Cycle Verification
VIN-specific quoteA complete fill/bleed and monitored running or after-run cycle is part of the repair, not an optional code clear.
Ask the estimate to identify which pump and loop the VIN calls A and which P2601 test failed. Do not combine coolant service, wiring, pump, sensor and controller alternatives into one predicted repair price.
Verification requires correct coolant level and bleeding, stable temperatures, expected pump command/response, no leaks and no returning current or pending P2601 through the specified thermal cycle.
P2601 OEM Differences and DIY Limits
Pump A may serve after-run, heater, turbo, hybrid, inverter or main engine cooling. Control may be relay, PWM, LIN or internal; the monitor may judge current, feedback, communication, flow or temperature.
Use Performance/Stuck Off for P2601 while explaining older rationality/range wording; do not merge it with open, low or high codes.
Pump role, coolant loop, control method, feedback and monitor logic vary widely between combustion, hybrid and electric applications.
Hot pressure, toxic coolant, automatic pumps/fans and nearby high voltage require controlled cool-down and model-specific procedures.
Current terminology is Performance/Stuck Off. Older documents may say range/performance or rationality, while P2600, P2602 and P2603 remain separate open, low and high electrical records.
- Save all-module codes, status and freeze frame.
- Inspect accessible connectors and recent work safely.
- Use VIN wiring and compare matching data.
- Stop when heat, voltage or movement exceeds your limits.
- Guess pins, thresholds, colors or locations.
- Probe live circuits without approved equipment.
- Force active, road or hot-system tests.
- Program or replace assemblies without proof.
Frequently Asked Questions About P2601
What does P2601 mean?
Why does the spreadsheet say Range/Performance?
Which pump is A?
Does P2601 prove the pump is bad?
Can I drive with P2601?
Is it the same as P2600/P2602/P2603?
Can UR1000 command the pump?
How is the repair verified?
Sources and Technical Review Notes
- Stellantis service bulletin hosted by NHTSA — Current P2601-00 Performance/Stuck Off wording and an OEM diagnostic path covering coolant, leaks/hoses, fuse, connectors, supply, LIN wiring, and pump replacement only after checks
- General Motors OBD certification document — P2601 auxiliary-coolant-pump rationality example based on coolant-temperature profile during enabled after-run operation; distinction from P2600/P2602/P2603 continuity faults
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