OBD Guide

P01EF

Engine Coolant Heater B Control Circuit Performance

P01EF is an OBD-II diagnostic trouble code meaning: Engine Coolant Heater B Control Circuit Performance. Common causes: coolant heater b malfunction, open or short circuit in wiring harness. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Extended engine warm-up time
  • Unstable engine operation at idle
  • Check Engine Light Illuminates

Causes

  • Coolant Heater B Malfunction
  • Open or short circuit in wiring harness
  • Relay or fuse problems
  • Engine control unit (ECU) malfunction

How to Fix

  1. Check the integrity of the wiring harness and connections
  2. Check fuses and relays associated with the heater
  3. Test coolant heater B for resistance
  4. If necessary, replace the heater or repair the wiring
  5. Reset the error and check if it returns

Related codes

Error P01EF by Vehicle Brand

FAQ

What does the P01EF code mean?

P01EF is an OBD-II diagnostic trouble code that indicates: Engine Coolant Heater B Control Circuit Performance

What causes a P01EF error code?

The most common causes of P01EF include: Coolant Heater B Malfunction; Open or short circuit in wiring harness; Relay or fuse problems; Engine control unit (ECU) malfunction.

How do I fix a P01EF diagnostic trouble code?

To fix P01EF: Check the integrity of the wiring harness and connections. Check fuses and relays associated with the heater. Test coolant heater B for resistance. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P01EF?

Limited driving only, diagnose soon

How much does it cost to fix P01EF?

The estimated repair cost for P01EF is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat