B2467

Code

Other B — Body

Aux Heater Cool Down Time Exceeded (may be con to a453-5 )

Brand: Other

Type: B — Body

Views: UK: 25 EN: 40 RU: 36

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty auxiliary heater control module or software/timer fault
Defective coolant temperature sensor (heater-side) or open/short in its wiring
Poor or corroded connection at connector A453 (pin 5) or other connector faults
Auxiliary coolant pump, heater relay or fan failed or not commanded
Restricted coolant flow through heater (blockage, closed valve, airlock)
Low coolant level allowing improper cooldown

Symptoms

Malfunction Indicator Lamp (MIL) or warning message for auxiliary heater
Auxiliary heater fails to show normal cooldown behavior or remains indicated as hot
Reduced or delayed cabin heating after auxiliary heater use
Possible engine or heater overtemperature warnings
Battery drain if heater remains active or components continue to run

What to check

Read stored codes and freeze frame data with a capable scan tool; note related heater and coolant codes
Visually inspect connector A453 (pin 5) and all auxiliary heater wiring for corrosion, looseness or damage
Verify coolant level and inspect for air in the heater circuit; pressure test if necessary
Check fuses, relays and power/ground supply to the auxiliary heater module and pump
Command heater off and on with diagnostic tool to observe behavior and monitor cooldown time
Monitor coolant temperature sensor values before, during and after heater shutdown with scan tool

Signal parameters

Aux heater control signals: typically 0–12 V supply and switched ground for relays; verify presence when commanded
Temperature sensor: NTC-type behavior (resistance decreases/increases with temp) or 0–5 V analog reference — verify change with temperature
Pump/fan control: PWM or switched 12 V signal when heater is active or during cooldown
Expected CAN messages: heater status, coolant temperature, pump status — check for valid periodic values
Diagnostic expected: temperature should fall steadily during proper cooldown; no change or incorrect steady value indicates sensor/wiring issue

Diagnostic algorithm

Retrieve and record all fault codes and freeze-frame data. Clear codes and attempt to reproduce the fault to confirm consistency.
Inspect and clean connector A453 and specifically pin 5. Ensure secure mating and no corrosion or bent pins.
With the engine cold, run auxiliary heater (where safe/legal) and use a scan tool to monitor coolant temp sensor values and heater status during startup, normal operation and shutdown.
Command heater off and measure cooldown time using live data. Compare to factory/expected behavior if available.
Check coolant level, bleed air from heater circuit, and inspect hoses/valve for restrictions. Pressure test cooling system if flow is suspect.
Verify auxiliary pump and fan operation by commanding them on with a diagnostic tool; check for proper voltage, ground and current draw.
Test the temperature sensor circuit for correct resistance/voltage at known temperatures and check continuity to the ECU/heater module (including A453-5). Repair wiring as required.
Inspect/replace heater relays, fuses or the auxiliary heater control module if control outputs are missing or incorrect.
If hardware and wiring check out, update module software/calibration and re-run tests. Clear codes and verify repair by reproducing normal cool-down timing.

Likely causes

Loose/corroded contact at connector A453 pin 5 interrupting sensor or command circuit
Coolant temperature sensor reading stuck or out-of-range preventing proper cooldown detection
Auxiliary pump or heater relay stuck so coolant/fan are not circulated during cooldown
Air in coolant or low coolant level preventing heat transfer and lengthening cooldown time

Fault status

⚠️ Status

Auxiliary heater cool-down time exceeded. Check heater control, coolant flow, temperature sensor and connector A453 pin 5 for faults or poor connection.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours