OBD Guide

U0635

Lost Communication With Hybrid/EV Battery Pack Coolant Temperature Sensor B

U0635 is an OBD-II diagnostic trouble code meaning: Lost Communication With Hybrid/EV Battery Pack Coolant Temperature Sensor B. Common causes: open or short circuit in the sensor circuit, coolant temperature sensor b malfunction. Estimated repair cost: $28–89.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$28–89 (est.)

Symptoms

  • Check Engine light comes on
  • Hybrid system power reduction
  • Incorrect battery temperature readings on the dashboard
  • Activation of emergency operation
  • Increased noise of the cooling system

Causes

  • Open or short circuit in the sensor circuit
  • Coolant temperature sensor B malfunction
  • Poor contact in the sensor connector
  • Wiring harness damage
  • Hybrid ECU malfunction

How to Fix

  1. Check the integrity of the sensor circuit (open/short circuit)
  2. Check the connectors and contacts of the sensor
  3. Test temperature sensor (resistance/signal)
  4. Replace the faulty sensor if necessary
  5. Check and reflash the ECU if it is suspected of being faulty

Related codes

Error U0635 by Vehicle Brand

FAQ

What does the U0635 code mean?

U0635 is an OBD-II diagnostic trouble code that indicates: Lost Communication With Hybrid/EV Battery Pack Coolant Temperature Sensor B

What causes a U0635 error code?

The most common causes of U0635 include: Open or short circuit in the sensor circuit; Coolant temperature sensor B malfunction; Poor contact in the sensor connector; Wiring harness damage.

How do I fix a U0635 diagnostic trouble code?

To fix U0635: Check the integrity of the sensor circuit (open/short circuit). Check the connectors and contacts of the sensor. Test temperature sensor (resistance/signal). For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U0635?

Limited driving only, diagnose soon

How much does it cost to fix U0635?

The estimated repair cost for U0635 is $28–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat