B13F4

Code

LAND ROVER B — Body

Electric heater - Control circuit 1

Brand: LAND ROVER

Type: B — Body

Views: UK: 22 EN: 32 RU: 21

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Page language: EN

Causes

Open circuit (broken wire, poor connector) in heater control wiring
Short to battery or short to ground on control or power feed
Blown fuse or failed relay supplying heater
Failed heater element or internal short in heater module
Faulty control module (HVAC module, BCM or dedicated heater controller)
Corrosion, water ingress or damaged connector pins

Symptoms

Heater function not working (no heat or reduced heat)
HVAC or seat heater warning message or DTC warning lamp
Intermittent operation of heater (works sometimes)
Blown fuse on repeated attempts to operate heater
Unusual odors or smoke in severe short-circuit cases

What to check

Read and record freeze frame/fault data with a diagnostic tool; clear code and attempt to re-create
Inspect related fuses and relays for continuity and correct operation
Visually inspect harnesses and connectors for damage, corrosion or water
Measure supply voltage at heater connector with ignition on and with heater commanded
Check ground continuity from heater module to chassis
Measure heater element resistance against specifications

Signal parameters

Control output type: switched battery feed or switched ground (depends on model)
Inactive voltage: approximately 0 V (ground-switched) or battery voltage (feed-switched) when off
Active voltage: battery voltage on feed or pulsed ground on ground-switched outputs when active
PWM control possible: duty cycle 0–100% to modulate heater power (frequency varies by model)
Heater element DC resistance: typically low (single-digit ohms to low tens of ohms) — consult vehicle spec

Diagnostic algorithm

Use a diagnostic scan tool to confirm B13F4, read any related codes and note system state. Clear the code and attempt to re-create the fault to confirm persistence.
Inspect all visible harnesses, connectors and the heater module for corrosion, damage or water ingress. Repair any physical damage.
Check fuses and relays for the heater circuit; replace any faulty items and re-test.
With ignition on, measure supply voltage at the heater power pin and check ground continuity at the heater connector. Voltage should be near battery voltage when supply is commanded.
Command the heater ON with a diagnostic tool and observe the control output at the module: verify correct switching (steady or PWM) and expected voltage levels. Use an oscilloscope if available to verify PWM characteristics.
Measure the heater element resistance. If open or shorted outside specification, replace the heater element/module.
If wiring and heater element check good but control output is absent or abnormal, test/replace the HVAC control module or BCM as per factory procedures.
After repairs, clear codes and perform functional test cycles to ensure code does not return.

Likely causes

Connector at heater module corroded or disconnected
Blown/partially blown fuse or failed relay in heater supply
High resistance or open in ground or supply wire causing improper current
Heater element failed (open or shorted) drawing abnormal current and triggering control fault
Control output transistor or driver in HVAC/BCM has failed

Fault status

⚠️ Status

Electric heater control circuit 1 - control circuit fault detected. The control module has detected an open, short, or abnormal load on the heater control circuit.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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Browse 413 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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B13F4 — Electric heater - Control circuit 1