1

Bulletin #: 2307
Part ID: 1950

Advanced Technical Information

Display of “Coolant temperature too high” in Group V6 and V8 Engines
Vehicles Affected
Models

Model Year

Model Type

VIN Range

Vehicle-Specific Equipment

Panamera

2017 - 2021

971

n/a

n/a

Macan

2019 - 2021

95B

n/a

all, except 4-cylinder

Cayenne

2019 - 2021

9YA, 9YB

n/a

n/a

Revision History
Revision

Release Date

Changes

0

April 1, 2023

Original document

Condition
Customer complains about “Coolant temperature too high” warning message, Instrument Cluster fault code
B19A750.

Figure 1 - Owner’s Manual Information for Over-Temperature Warning (B19A750)

Technical Background
The aforementioned warning message in the instrument cluster (IC) only displays when the coolant temperature
exceeds the warning threshold. The vacuum changeover valve controlling the water pump’s sleeve in the aforementioned engines is known to intermittently stick, thus causing the overheat warning in the IC.

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1

Bulletin #: 2307
Part ID: 1950

Advanced Technical Information

Figure 2 simulates an overheat condition by overriding the changeover valve for the coolant pump sleeve. For this
simulation, the valve’s electrical connection to the DME remained intact, but the simulation removed the valve
from the vacuum lines, forcing the coolant pump’s sliding sleeve to remain in the blocked flow position (no coolant
circulation). Thus, the simulation’s data of Figure 2 shows a ‘forced’ overheat condition from cold-start. In this simu-
lation, the DME commands the changeover valve to switch, opening the pump’s sleeve, allowing coolant to circulate
(if the valve was connected). The blue series line shows this switch around 500 seconds of engine run time. Because
the valve is not in-line with pump’s vacuum supply (removed except electrically), the sleeve never opens, and the IC
warning “Display of coolant temperature too high, active” results after approximately 25 minutes.

Figure 2 - Tester Tracing of Forced Overheating from Overridden Water Pump Changeover Valve

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Bulletin #: 2307
Part ID: 1950

Advanced Technical Information

1

Figure 3 - Fault Code B19A750 in the Instrument Cluster
The intent of Figure 3 is to help Service Departments interpret VALs when the fault B19A750 is in the instrument
cluster’s fault memory. Intuitively, Box 1.1 within Figure 3 shows the corresponding environmental fault data which
results when the engine temperature does not exceed the warning threshold at the time of VAL. Box 1.2, “13_Fault
display in the instrument cluster” shows the warning is not active in the IC at the time of the VAL. Nonetheless, it
is certain the fault displayed to the operator when the engine’s temperature exceeded the warning threshold, as
shown in Figure 2. Box 1.3 “20_Fault occurrence – time stamp: 37_Fault shedding counter” indicates the number
of ignition cycles (KL 15) since the fault last occurred. When the fault first occurs, the value for this environmental
data label begins at 255. Each successive KL 15 DME switch-on condition in which the fault is not active causes
this counter to index downwards. In the example of Figure 3, we can observe that it has been 121 ignition cycles
since the warning last occurred.

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Bulletin #: 2307
Part ID: 1950

Advanced Technical Information

1

Service Information
Please follow the function test as outlined in “TI, 1950 Warning Message “Coolant Temperature Too High”: Checking
Coolant Pump and Change-Over Valve (173/21)” The vacuum changeover valve controlling the water pump’s sleeve
in the aforementioned engines is known to intermittently stick, thus causing the overheat warning in the IC. Therefore, it is imperative to check its function as thoroughly as possible under various temperature conditions, because
temperature can play a role in its behavior.
Please follow the referenced TI and appropriate workshop manuals for any work deemed necessary.

Warranty
As always, please document the repair completely in PQIS.
For this repair, please code the “cause” as follows:
Cause location:
19500 Coolant pump
Cause symptom:
1611 No function

Search Items
Coolant leak, water pump, change-over valve, switching valve, overheating, temperature.

Important Notice: Technical Bulletins issued by Porsche Cars North America, Inc. are intended only for use by professional automotive technicians who have attended Porsche service training courses. They are
written to inform those technicians of conditions that may occur on some Porsche vehicles, or to provide information that could assist in the proper servicing of a vehicle. Porsche special tools may be necessary in
order to perform certain operations identified in these bulletins. Use of tools and procedures other than those Porsche recommends in these bulletins may be detrimental to the safe operation of your vehicle, and
may endanger the people working on it. Properly trained Porsche technicians have the equipment, tools, safety instructions, and know-how to do the job properly and safely. Part numbers listed in these bulletins
are for reference only. The work procedures updated electronically in the Porsche PIWIS diagnostic and testing device take precedence and, in the event of a discrepancy, the work procedures in the PIWIS Tester
are the ones that must be followed.

A13168
©2023 Porsche Cars North America, Inc.

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