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DTC codes / U06xx · Network communication / U0698

U0698Lost Communication With Coolant Pump E

U0698 is a network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has stopped receiving messages from the coolant pump module designated as Coolant Pump E. The monitoring module expected regular status broadcasts from that pump controller and detected that the messages timed out or disappeared entirely, so it flagged the loss of communication rather than a mechanical pump failure.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • Illuminated check engine light or service vehicle soon message on the dashboard
  • Often no symptoms besides the warning light, especially if the pump is still running on default logic
  • Engine temperature gauge behaving erratically or reading higher than normal
  • Reduced engine power or limp-home mode triggered by the powertrain module
  • Cooling fan running constantly or not at all because the pump status is unknown
  • Overheating warning or coolant temperature warning lamp during extended driving

Common causes, most likely first

  1. Faulty or failed coolant pump control module or the pump's integrated electronics
  2. Damaged, corroded or disconnected wiring and connector pins at the pump harness
  3. Blown fuse or poor ground supplying the coolant pump circuit
  4. CAN bus wiring fault such as an open, short or chafed data line between the pump and the network
  5. Low or unstable battery voltage causing the pump module to drop offline intermittently
  6. Failed pump motor that no longer powers up and therefore cannot communicate
  7. Software or configuration mismatch after module replacement without proper initialization

How to diagnose and fix it

  1. Scan all modules for stored and pending codes to confirm U0698 is active and identify which module reported it
  2. Inspect the coolant pump connector and harness for corrosion, pushed pins, chafing and loose terminals
  3. Check the pump circuit fuse and verify battery voltage and ground integrity at the pump connector
  4. Measure CAN bus voltage and resistance at the pump connector to confirm the data lines are intact
  5. Command the coolant pump on with a bidirectional scan tool and watch for live data and communication recovery
  6. Substitute a known-good pump or module only after wiring and power checks pass, then clear codes and verify communication
  7. Relearn or initialize the replacement module and road test to confirm the code does not return

Why the pump talks before it pumps

  • Many coolant pumps on modern engines are electrically driven and contain their own control module, so a communication code can appear even when the impeller still turns and cooling works normally
  • A weak or aging battery is a frequent hidden cause because the pump module drops off the network during cranking and sets a communication fault that looks like a failed pump
  • Technicians often replace the pump when the real fault is a single corroded terminal or a chafed CAN wire near the pump bracket, so always load-test the circuit before condemning the part
  • U0698 can be stored by a body or chassis module rather than the engine computer, so reading only the powertrain codes may miss the module that actually logged it
  • After a pump replacement, some vehicles require module initialization or a network reflash, and skipping that step leaves the code returning even with a healthy new pump

Can I keep driving with U0698?

You can usually drive a short distance to a workshop if the temperature gauge stays normal, but avoid long trips, heavy loads and stop-and-go traffic. Pull over and shut the engine off immediately if the temperature gauge climbs or an overheating warning appears, because a non-communicating pump may also have stopped circulating coolant.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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