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Preview Solution CBR-2526-4
Parking Heater Inoperative - VN (4) - PR
(4) - AN (4)
Published 11 November 2025

Valid For
Volvo Chassis - VN (4)
Mack Chassis - PR (4), AN (4)
Model Year - 2025 to Current

The purpose of this CBR is to address driver complaint of parking heater
inoperative.

NOTE: As a preventative maintenance action, please perform a
parking heater power reset on ALL VN(4) and PR(4) trucks
equipped with the Eberspacher unit. This will reset the fault
count in the parking heater and mitigate the chance that the
parking heater will lock over the course of the winter. The
appropriate fuse for the power reset is fuse F14 in the Cab FRC
(pictured below). For procedure please navigate to IMPACT,
under Info type use Bulletins/Information, select Eberspacher
Auxiliary Heater Troubleshooting and Repair Manual and
navigate to section 4.3 Unlocking the control box.

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This CBR will address 2 different parking heater concerns: Lock Outs and
Time Outs.

Lock Outs:
1. Symptoms:
Determine if the parking heater is locked out by pressing the parking
climate button on the Driver-Environment Control Module (DECM). If
the light on the button remains lit for 3-5 seconds and then turns off, the
parking heater is locked. NOTE that DTCs are not a reliable means of
determining if the parking heater is locked.
2. Resolution process
a. Attempt to Clear the Over Temperature Lock
The parking heater may lock out due to 10 consecutive settings of
an internal over temperature fault.
To resolve a parking heater lock for over temperature faults,
please perform a power cycle as per the Eberspacher Auxiliary
Heater Troubleshooting and Repair Manual and navigate to
section 4.3 Unlocking the control box.
After the reset is compete:
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i. If the parking heater functions normally, the lock has been
cleared. Refer to step 3 before releasing the truck to the
customer.
ii. If the parking heater remains locked, proceed to step b.
b. Attempt to Clear Locks from Other DTCs
Other DTCs internal to the Eberspacher unit may lock the parking
heater after 10 consecutive settings. NOTE that these locks
cannot be removed with a power cycle – the PTT operation 875006-03-03 Parking heater function must be used.
NOTE: There is currently one potential root cause for these
additional DTCs - Please ensure that the fuel delivery line to the
parking heater is not blocked or obstructed before attempting to
unlock the unit.
If the parking heater is locked, the Parking heater function (step 2)
will show a red error circle. This should enable the ability to click
the play button on the ‘Unlock the heater interlock’ step.

i. If the interlock succesfully clears, test the parking heater to
ensure normal functionality. If the parking heater functions
normally, the lock has been cleared. Refer to step 3 before
releasing the truck to the customer.
ii. If the option to clear the interlock remains grayed out,
proceed to step c.
NOTE: If the option to clear the interlock remains
grayed out, DO NOT make additional attemps to run the
operation. Repeat use of ‘Fill Fuel Lines’ (step 1) will
cause fuel leaks

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c. If Unable to Clear the Lock from PTT
If Parking heater function (step 2) shows an error and the option to

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unlock the interlock (step 3) remains grayed out, please open an
eService case.
3. Mitigating Future Locks
To mitigate the occurrence of future parking heater locks, please instruct
the customer in the following information:
a. Over Temperature faults are set specifically during parking heater
cleaning sessions. When a parking cleaning session is active,
ensure that:
i. The inlet and outlet vents are not obstructed
ii. The luggage compartment is not over-cluttered
iii. The windows and luggage compartment are open to reduce
ambient air temperature

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b. Customers can also be instructed to ignore parking heater
cleaning requests for the duration of the winter. These cleanings are
unnecessary while the parking heater is under regular useage during
the cold season.

Time Outs
1. Symptoms:
eService cases have been submitted with customer complaints of the
parking heater shutting off overnight. NOTE that in most instances, this
should not occur due to over temperature or lock outs.
2. Resolution Process
a. Clarify the Customer Complaint
The parking climate system was designed to automatically shut off
after 10 hours of use. Speak with the customer to determine if this
is the cause of the overnight shut off.
i. When did the customer activate parking climate?
ii. When did the customer notice that the parking climate
turned off?
b. Submit an eService Case
Please submit an eService Case with a detailed explanation of the
above information from the customer. Technical Support will want
to know when the parking climate was activated and when it
turned off before proceeding with the case.
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