U0155 — Lost Communication with Instrument Panel Cluster (IPC)

What it means

U0155 is a generic network DTC (second digit 0) indicating that one or more controllers stopped receiving the required messages from the instrument panel cluster (IPC) over the vehicle network. On most light-duty platforms the IPC participates on high-speed CAN (HS-CAN ~500 kbps) (e.g., GM GMLAN High-Speed, Ford CAN-C) and exchanges data with the ECM/PCM, TCM, ABS/EBCM, EPAS/PSCM, BCM, SRS/RCM, telematics/radio, and a gateway. OEMs may log U0155 from any dependent module (IPC missing messages), and some platforms also document benign, ignition-on timing cases where U0155 may set briefly as history. OBD-Codes.com+2NHTSA+2

Typical symptoms

  • Cluster inoperative or intermittent; dead gauges/PRNDL, erratic chimes/messages
  • Multiple warning lamps (ABS/ESC, airbag, steering, “Service” messages)
  • Global scan shows U-codes across several modules; IPC appears offline/intermittent on topology
  • In severe network faults: intermittent no-crank, stalls, or loss of features due to cascading comms faults. OBD-Codes.com+1

Why it sets (representative OEM logic)

  • Message timeout from IPC: Supervising modules (gateway/ECM/BCM/IPC peers) do not receive required IPC frames within calibrated timers → set U0155. (Some OEMs mark subtypes like “Missing Message”.) OBD-Codes.com
  • Network/physical-layer faults: Opens/shorts, incorrect termination, or a node going error-passive/bus-off prevent delivery of IPC messages. OEM HS-LAN procedures specify ~60 Ω ±5 Ω key-off across HS-CAN (two 120-Ω terminators in parallel); <60 Ω suggests a short/extra terminator, >60 Ω suggests an open/missing terminator. NHTSA
  • OEM examples/nuance:
    • GM 08-07-30-021H groups U-codes (incl. U0100/U0121/U0140) under HS-GMLAN communication concerns—same root causes apply to U0155. NHTSA
    • Toyota documents U0155xx “Missing Message” between the ECM and combination meter (IPC) with detection time windows (e.g., ≥2.6 s). EstimateCA
    • Subaru notes that a branch-bus open can leave global HS-CAN resistance at ~60 Ω yet one node (e.g., IPC) remains offline, reinforcing the need for branch isolation. NHTSA
    • GM (timing note): U0155 stored only as history in the Passenger Presence System can stem from key-on timing between PPS and IPC and may be disregarded for PPS diagnostics. NHTSA

Common root causes

  1. Power/ground loss at IPC (blown fuse, poor ground, low battery/charging voltage)
  2. HS-CAN wiring faults (opens/shorts to B+/ground, CAN_H↔CAN_L short), damaged splices/junctions
  3. Termination problems on HS-CAN (failed/missing 120-Ω end → total ≠ ~60 Ω)
  4. Connector faults at IPC (pin tension/corrosion; water intrusion behind cluster or junction blocks)
  5. Internal IPC/transceiver failure intermittently entering error-passive/bus-off
  6. Aftermarket device interference (DLC dongles, trackers, alarm/remote-start/audio) affecting network or IPC power feeds. OBD-Codes.com+1

Professional diagnostics (step-by-step)

Network overview & scan strategy

  • Perform a global DTC scan. Note every U-code and which modules are offline. Use your scan tool’s topology/gateway map to confirm whether the IPC enumerates and which network segment carries it. If many HS-CAN nodes are down, suspect a bus-wide or power/ground issue; if only IPC is missing, suspect branch/power/connector faults local to the cluster. OBD-Codes.com

Power/ground checks at the IPC

  • Verify B+, IGN feed, and grounds under load at the IPC (target ground drop ≤100–200 mV). Correct low-voltage or poor ground issues before network testing—an unpowered IPC presents as “lost comms.” OBD-Codes.com

Bus integrity tests (HS-CAN)

  • Key-off resistance: Measure between DLC pins 6 & 14. Expect ~60 Ω ±5 Ω.
    – >60 Ω ⇒ open/missing terminator; <60 Ω ⇒ short/extra terminator. Remember: a branch-open can still read 60 Ω globally yet leave the IPC offline—don’t stop at the DLC reading. NHTSA+1
  • Key-on voltage / basic physical layer: At rest, CAN common-mode ≈ 2.5 V, with small opposite deviations (~2.6 V CAN_H / 2.4 V CAN_L). A line stuck near 0 V/5 V or no differential toggle indicates a hard fault. (Follow OEM HS-CAN flow.) NHTSA

Segment/branch isolation

  • Unplug nodes or pull fuses feeding HS-CAN sub-nets/junctions one at a time while observing when comms recover (modules reappear, IPC returns). Use OEM diagrams to split the network and identify star points. Nissan’s generic CAN flow chart is a useful OEM example of stepwise isolation per module. NHTSA

Connector/terminal & harness inspection (IPC/junctions first)

  • Perform pin-drag tests; inspect IPC connectors and nearby junction blocks for backed-out pins, corrosion/water, prior repair splices, and harness chafe. Repair/repin and restore proper twisted-pair routing. NHTSA

Aftermarket device audit

  • Temporarily remove DLC-attached devices (trackers/insurance dongles) and any add-ons spliced into HS-CAN or IPC power. Re-evaluate bus stability—GM documents many electrical/network concerns tied to add-ons. NHTSA

Module actions (only after bus integrity is proven)

  • If wiring/termination/power are good and IPC remains offline, check for calibration/software updates; then replace/initialize the IPC or gateway per OEM programming. Be aware of timing-related “history only” U0155 cases as noted by GM (don’t chase a non-issue). NHTSA

Verified fixes

  • Restore IPC power/grounds; correct low-voltage and ground-eyelet issues
  • Repair HS-CAN wiring (opens/shorts), fix splices/junctions; maintain twist and routing
  • Restore proper termination (two 120-Ω ends ≈ 60 Ω total); correct star/junction faults
  • Clean/repin IPC connectors; address pin tension/corrosion; seal water ingress paths
  • Remove/rewire interfering aftermarket DLC/telematics devices
  • Reflash/initialize or replace the IPC/gateway only after proving the network healthy
  • Clear codes, drive cycle, and re-scan to confirm. NHTSA

Sources

  • OBD-Codes — U0155 (Lost Communication with Instrument Panel Control/IPC Module) — generic definition, scan/diagnosis framing. OBD-Codes.com
  • GM/ACDelco via NHTSA — Diagnostic Tips: Diagnosing High-Speed LAN Concerns — OEM HS-CAN method; ~60 Ω ±5 Ω spec; guidance for “shorted/higher than 60 Ω” interpretations. NHTSA
  • GM 08-07-30-021H (2015) — HS-GMLAN communication concerns; field symptoms (IP gauge fluctuation, chimes, multiple lamps) and network-first diagnostics. NHTSA
  • Toyota (Mitchell portal excerpt) — U015587 “Lost Communication with IPC — Missing Message”, detection time example (≥ 2.6 s). EstimateCA
  • Subaru — Electrical Systems Operation & Diagnosis (2013) — branch-open nuance: global 60 Ω can remain normal while a module on the branch (e.g., IPC) loses comms; isolate branches. NHTSA
  • Nissan NTB13-027a — CAN Communication Network Diagnostic Flow Chart — OEM stepwise isolation for CAN DTCs (repeat per affected module), applicable method for U-code diagnosis. NHTSA