B1221

Code

LAND ROVER B — Body

Left seat heater output - open circuit

Brand: LAND ROVER

Type: B — Body

Views: UK: 21 EN: 43 RU: 21

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open circuit in the left seat heater element (broken heating wire)
Open or corroded connector or terminal to the seat heater
Broken, pinched, or disconnected wiring between seat and control module
Blown fuse or tripped circuit protection for seat heater circuit
Faulty seat heater switch or wiring to the switch
Faulty seat/comfort control module or internal driver output failure

Symptoms

Left seat heater produces little or no heat
Seat heater indicator for left seat may flash or show a fault
DTC B1221 stored in body/seat control module
Possible loss of seat heating function while right seat still works
No current draw from left heater circuit (measured) despite switch on

What to check

Read and record freeze frame and all stored DTCs with a capable scan tool
Check fuse(s) for seat heaters and replace if blown; inspect fuse holder
Visual inspection of seat cushion and seat base connectors for corrosion, water, damage
Check connector mating faces and pins/pockets for damage or poor contact
Measure voltage at heater supply pin at seat connector with switch ON
Measure continuity/resistance of heater element (seat removed if needed)

Signal parameters

Battery supply at heater connector: ~12 V (key ON, seat heater ON)
Element resistance (typical range): roughly 2–10 ohms (varies by design) — open = infinite/OL
Control signal: module may switch ground or use PWM; expected switching present when heater commanded
Fuse rating: commonly 10–30 A depending on model (check OEM spec)
Ground continuity: near 0 ohms between seat ground and chassis
No current flow (0 A) from left heater circuit when open fault present

Diagnostic algorithm

Verify DTC B1221 with a scan tool and note freeze-frame data. Clear codes and attempt to re-create the fault to confirm.
Confirm operation of seat heater controls (switch/steering menu) and observe live data for left heater command and status.
Visually inspect fuse(s) and seat-related connectors for damage, corrosion, or water ingress. Replace or repair as needed.
With connector unplugged, measure supply voltage at the seat-side connector pin with heater ON. If no supply, trace back to fuse/relay/control module.
Measure continuity/resistance of the left seat heater element. If infinite/OL, the heater mat/element is open and should be replaced.
Check continuity of wiring between seat connector and body/seating control module for opens. Wiggle harness while monitoring to find intermittent faults.
Verify ground integrity for the seat heater circuit. Repair any high-resistance or corroded grounds.
If wiring, connectors and heater element are good, check output driver at the control module for correct switching (voltage or PWM) when heater is commanded. If no driver activity and inputs are correct, suspect module fault.
After repairs, clear codes, operate seat heater through all levels and confirm no return of B1221 and proper heating of left seat.
If intermittent or water-damaged seat suspected, replace seat cushion/element and dry/repair affected components per OEM guidance.

Likely causes

Broken heater element wire inside the seat pad (open)
Disconnected or corroded connector at the seat heater or module
Blown fuse or open circuit protection device
Damaged wiring (chaffed/pinched) between seat and body control module
Faulty seat control module driver (less common)

Fault status

⚠️ Status

Left seat heater output circuit open detected by seat/body control module. Left seat heating disabled until fault is repaired.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

Repair manuals

Manual library for LAND ROVER

413

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

LAND ROVER

Your experience will help others

+100 karma for a short comment :)

Was this AI description helpful?

Your feedback helps improve AI descriptions.

👍 Like 0 👎 Dislike 0

Send to email

B1221 — Left seat heater output - open circuit