🌡️Heat Pump

E12

York · YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor

York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor E12 Error Fix: Communication Error Between Indoor and Outdoor Units

The indoor and outdoor units are unable to communicate properly, often due to wiring faults or control board issues. This causes the system to malfunction or shut down.

High severity2 fixes available

Quick Answer

Error E12 on the York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor means: Communication Error Between Indoor and Outdoor Units. The top-ranked community fix is “Replace indoor control board” (hard difficulty, ~90 min, DIY cost: $200-$250). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · heat pump

Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.

Root Cause Analysis

Electrical Fault → Wiring Harness DamagedPrimary

Control Board Failure

When to Call a Professional

While many heat pump repairs can be done safely at home, consider hiring a qualified technician if:

This is a high severity error — continued use may cause damage or a safety hazard
The repair involves electrical wiring, gas lines, or refrigerant
You've tried the top-ranked fix and the error persists
You smell gas, see sparking, or notice water leaking
The repair requires specialized tools you don't have
Your appliance is still under manufacturer warranty

Average professional repair cost for this issue: $400-$600.

Other York Models with Error E12

DERA-P036N07 HP 16 SEER

heat_pump · 2 fixes

GM9S080B12MP11 80,000 BTU 96% AFUE Single-Stage Upflow Gas Furnace

furnace · 2 fixes

TM8E100C20MP11 100,000 BTU 80% AFUE Single-Stage Upflow Gas Furnace

furnace · 2 fixes

TM9V080B12MP11 80,000 BTU 96% AFUE 2-Stage Variable-Speed Gas Furnace

furnace · 2 fixes

YCG42B21S 3.5 Ton 14 SEER Affinity Series Air Conditioner with Scroll Compressor

air_conditioner · 2 fixes

YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant

heat_pump · 2 fixes

Other York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor Error Codes

High Pressure Switch Trip

2 fixes

E10

Indoor Coil Freeze Warning

2 fixes

E11

Compressor Start Relay Failure

2 fixes

E13

Outdoor Ambient Temperature Sensor Failure

2 fixes

E14

High Limit Thermostat Open

2 fixes

E15

Freeze Protection Sensor Open

Drain Pump Failure

Auxiliary Heater Failure

2 fixes

People Also Ask About York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor Error E12

What does error code E12 mean on a York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor?

Error code E12 on the York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor means: Communication Error Between Indoor and Outdoor Units. The indoor and outdoor units are unable to communicate properly, often due to wiring faults or control board issues. This causes the system to malfunction or shut down.

How do I fix error code E12 on my York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor?

The most successful fix is "Replace indoor control board" (hard difficulty, ~90 minutes). Estimated DIY cost: $200-$250. HomeMD has 2 community-ranked fixes for this error.

Is error code E12 on a York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor serious?

This error is rated high severity. You should address it promptly — continued use could cause damage or safety concerns.

Can I fix York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor error E12 myself?

Yes — the top-ranked community fix ("Replace indoor control board") is rated hard difficulty and takes about 90 minutes. Tools needed: Phillips screwdriver, Multimeter.

How much does it cost to repair York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor error E12?

DIY cost: $200-$250. Professional repair typically costs $400-$600. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor have?

The York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor has 8 other known error codes, including: E1 (High Pressure Switch Trip), E10 (Indoor Coil Freeze Warning), E11 (Compressor Start Relay Failure), E13 (Outdoor Ambient Temperature Sensor Failure), E14 (High Limit Thermostat Open), and 3 more.

Which other York models have the E12 error?

Error code E12 also appears on 6 other York models: DERA-P036N07 HP 16 SEER, GM9S080B12MP11 80,000 BTU 96% AFUE Single-Stage Upflow Gas Furnace, TM8E100C20MP11 100,000 BTU 80% AFUE Single-Stage Upflow Gas Furnace, TM9V080B12MP11 80,000 BTU 96% AFUE 2-Stage Variable-Speed Gas Furnace, YCG42B21S 3.5 Ton 14 SEER Affinity Series Air Conditioner with Scroll Compressor, YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor have?

The York YHG42B21S 3.5 Ton 14 SEER 10 HSPF Affinity Series Heat Pump with Variable-Speed Compressor has 8 other known error codes:

E1 — High Pressure Switch Trip (2 fixes)
E10 — Indoor Coil Freeze Warning (2 fixes)
E11 — Compressor Start Relay Failure (2 fixes)
E13 — Outdoor Ambient Temperature Sensor Failure (2 fixes)
E14 — High Limit Thermostat Open (2 fixes)
E15 — Freeze Protection Sensor Open (2 fixes)
E16 — Drain Pump Failure (2 fixes)
E17 — Auxiliary Heater Failure (2 fixes)

Which other York models have the E12 error?

Error code E12 also appears on 6 other York models:

DERA-P036N07 HP 16 SEER (heat pump) · 2 fixes
GM9S080B12MP11 80,000 BTU 96% AFUE Single-Stage Upflow Gas Furnace (furnace) · 2 fixes
TM8E100C20MP11 100,000 BTU 80% AFUE Single-Stage Upflow Gas Furnace (furnace) · 2 fixes
TM9V080B12MP11 80,000 BTU 96% AFUE 2-Stage Variable-Speed Gas Furnace (furnace) · 2 fixes
YCG42B21S 3.5 Ton 14 SEER Affinity Series Air Conditioner with Scroll Compressor (air conditioner) · 2 fixes
YZH36B21S 3 Ton 16 SEER 9.5 HSPF Heat Pump with Environmentally Friendly Refrigerant (heat pump) · 2 fixes

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