U0155
Lost Communication With Instrument Panel Cluster (IPC) Control ModuleU0155 is a generic OBD-II network diagnostic trouble code: Lost Communication With Instrument Panel Cluster (IPC) Control Module. It is logged by the engine control unit when the network monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What U0155 means
U0155 is a generic network communication fault defined as "Lost Communication With Instrument Panel Cluster (IPC) Control Module." It is set when one or more control modules on the vehicle's high-speed CAN bus (typically operating at ~500 kbps) stops receiving the expected message frames from the IPC within the prescribed timeout window. The IPC normally broadcasts vehicle speed, odometer, and warning lamp status to the engine control module, transmission control module, ABS, and body control module, so its absence can cascade into secondary faults across multiple systems.
The most frequent root causes are power or ground faults at the IPC — a blown fuse, corroded ground eyelet, or low battery voltage that prevents the module from operating its CAN transceiver — and physical wiring faults on the CAN bus itself such as an open, short to battery, or short to ground on the CAN-High or CAN-Low lines. Connector-level problems (backed-out pins, water intrusion, pin corrosion) at the IPC harness plug are equally common. Internal IPC hardware or transceiver failure accounts for a smaller proportion of cases. Aftermarket DLC-attached devices (GPS trackers, insurance dongles) that interfere with the bus are an often-overlooked trigger.
A key-off resistance measurement between OBD-II DLC pins 6 and 14 should read approximately 60 Ω; a reading significantly above this indicates an open in the bus, while a reading significantly below indicates a short between CAN-High and CAN-Low. This test, combined with a full multi-module network scan to map which modules are offline, is the correct starting point before any component is replaced.
Common causes
Most-frequently reported root causes when U0155 is logged.
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1
Blown fuse or faulty relay supplying power to the IPC.
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2
Corroded, loose, or broken ground connection at the IPC.
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3
Open circuit, short to battery, or short to ground on the HS-CAN wiring harness.
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4
Short circuit between CAN-High and CAN-Low lines (bus collapse).
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5
Corroded, backed-out, or water-damaged pins in the IPC harness connector.
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6
Failed or damaged CAN transceiver inside the IPC module.
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7
Aftermarket device plugged into the OBD-II port that disrupts CAN bus communication.
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8
Low battery voltage or charging system fault causing intermittent module dropout.
Symptoms drivers notice
How to diagnose U0155
A typical diagnostic flow when this code is present.
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1
Perform a full multi-module DTC scan and record all U-codes along with the modules reporting them to identify the scope of the network fault.
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2
Measure key-off resistance between OBD-II DLC pins 6 (CAN-High) and 14 (CAN-Low); expect approximately 60 Ω — higher indicates an open, lower indicates a short.
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3
Verify battery voltage (12.4 V minimum key-off) and charging system output; correct any power supply issues before continuing.
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4
Inspect IPC fuse(s) and confirm ignition and battery supply voltages at the IPC connector are within specification.
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5
Test IPC ground connections for voltage drop under load; maximum allowable drop is typically 200 mV.
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6
Visually inspect the IPC harness and connector for chafed wiring, water intrusion, pin corrosion, or backed-out pins; perform a pin-drag test on all IPC connector terminals.
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7
Temporarily remove any aftermarket DLC-attached devices and re-scan to determine if they are contributing to the fault.
Related network codes
- U0100 — Lost Communication With ECM/PCM A
- U0101 — Lost Communication with TCM
- U0102 — Lost Communication with Transfer Case Control Module
- U0103 — Lost Communication With Gear Shift Module
- U0104 — Lost Communication With Cruise Control Module
- U0105 — Lost Communication With Fuel Injector Control Module
Frequently asked questions
Can U0155 cause a no-start condition?
Yes, in some vehicles the PCM or immobilizer system cross-checks with the IPC for vehicle-speed or security data. If the IPC is completely offline, some modules may refuse to enable fuel injection or the starter circuit, resulting in a no-crank or no-start.
Is U0155 always caused by the instrument cluster itself?
Not necessarily. The code means the IPC is not being heard on the network, which can be caused by a wiring fault, a blown fuse, or a failed CAN terminator rather than the cluster module itself. Always verify power, ground, and bus integrity before condemning the IPC.
Will U0155 trigger the MIL (check engine light)?
U0155 is a U-code (network/communication fault), so it typically triggers a warning lamp — often a general warning or a check-engine light — rather than a specific MIL, but this varies by manufacturer. It will appear in the stored DTC list of all modules that lost IPC communication.
Can a weak battery cause U0155?
Yes. Low battery voltage or a charging system fault can cause the IPC to brown out intermittently and drop off the CAN bus, setting U0155 as a history code. Always test battery and alternator output before diagnosing wiring or module faults.
Disabling U0155 in software
RaceTune can permanently disable U0155 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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