Trane Air Conditioner Error Codes List: Every Code Explained

Every Trane air conditioner error code we could verify against Trane's own documentation — what it means, what usually causes it, and the first fix to try — in one table. Codes differ between model series, so treat your model's tech sheet as the final word.

How to read and retrieve error codes on Trane air conditioners

Central variable-speed units: read the two LEDs on the Integrated Variable Speed Control board — green STATUS gives state by rate (slow = standby, medium = call for capacity, fast = power-up delay, solid = test mode, 1 flash per 4 s = hard lockout; the STATUS light is dark in Trane Link mode) and amber COMM counts communicating devices when slow, or flashes fast on loss of communication. The actual fault is a plain-language message on the CDA display adapter at the unit and in the XL1050/UX360 alert history — there is no numbered table to look up, and Trane's numbered Alert Code Addendum is a dealer document. Ductless units: read the code on the indoor display (RUN lamp confirms), and remember the outdoor power board also has its own 1–17 blink-count list in the service manual — indoor display and outdoor board are two views of the same fault.

The complete Trane air conditioner error code list

How to reset / clear error codes on Trane air conditioners

The variable-speed outdoor control's power-up delay (STATUS fast flash) clears itself when its timing expires; a hard lockout (STATUS 1 flash every 4 s) holds until the underlying fault is corrected — the stored CDA/control message, not power cycling, is the way out. On the ductless platform, sensor failures clear automatically when the sensor reads normally again, outdoor-related codes may linger on the display up to 2 minutes after recovery, and the escalated drive fault E9 is the documented exception: it latches and needs an off/on cycle AFTER the drive fault is repaired. Conventional XR/XL units have no lockout codes to reset because they publish no code system at all.

How to diagnose any Trane air conditioner code

Work the problem in this order — and stop where refrigerant, compressors or mains wiring begin, because those are licensed work: (1) record the code exactly as displayed, including whether it came from the indoor display, the wired/wireless remote check mode, or an LED pattern on the outdoor unit — the three are different reports; (2) check the homeowner basics first: the air filter (a matted filter ices coils and imitates sensor and refrigerant faults), the condensate drain and float switch, the outdoor coil clear of leaves and debris, and both breakers fully on; (3) power-cycle once at the breaker, then run the mode the code interrupted and watch the sequence — indoor fan, outdoor fan, compressor start — because the stage that never starts names the fault family; (4) on mini-splits, retrieve the stored check code with the remote's diagnosis function before clearing anything, and write down the full code including its letter family; (5) a code that returns in the same mode is an active fault. Refrigerant charge, sealed-system and board-level work is professional work — an undercharged system re-iced after a reset is being damaged, not cured.

Why the Trane AC table looks different: LEDs and text, not numbers

Anyone arriving from a web search expects a Trane air conditioner to produce numbered error codes, and Trane's variable-speed central systems — the XV family on Trane Link or ComfortLink II — simply do not work that way in any document Trane publishes for them. The outdoor unit's Integrated Variable Speed Control board carries two LEDs. The green STATUS LED reports state by rate: slow (1/sec) is standby, medium (2/sec) is a call for capacity, fast (5/sec) is the power-up delay, solid is test mode, and one intermittent flash every four seconds is a hard lockout (in Trane Link mode the STATUS light is not used at all). The amber COMM LED reports the communicating bus: flashing slowly once per device it is literally counting the devices it can see, and flashing fast it is announcing loss of communication. The faults themselves are not numbers on this platform — they are plain-language messages shown on the CDA display adapter wired to the board and stored in the communicating control's alert history. This is why the honest Trane central-AC table is short: seven LED indications, each verified identically in two editions of Trane's Installer's Guide 18-BC106D1, plus a diagnostic method (read the CDA message) rather than a code list. The numbered alerts that fill third-party websites — 79, 91, 104, 126, 158 — do exist as internal Trane alert numbers, but their definitions live in a dealer-only Alert Code Addendum that Trane does not publish; Trane's own Trane Home support page states plainly that support cannot decipher error codes and refers owners to their dealer, and third-party attributions for the same numbers contradict each other (126 alone is sold as a communication fault, an equipment-mismatch fault, and a low-temperature lockout in different places). Publishing any of those numbers with a confident meaning would be inventing Trane documentation, so they sit in this hub's UNVERIFIED list with the reason stated.

Conventional Trane AC has no code table — and that is a finding, not a gap

The second Trane reality is the conventional fleet: XR and XL condensers and packaged units that run on ordinary 24 V thermostat calls. Their Service Facts documents — checked here for the 4TTR6 condenser family and a 4TCC packaged unit — contain installation data, charging procedures and genuinely useful troubleshooting flowcharts (work the contactor circuit, check the transformer and fuse, verify the call), but no fault-code table and no LED flash-code list, because the equipment has no fault-reporting layer to document. The control is a contactor; the diagnostics are a multimeter. This hub's Batch 6 research reached the same conclusion for Trane heat pumps and kept that cluster deliberately system-level, and the deeper AC-side dig ordered for this batch confirms it rather than overturning it. The practical consequence for owners and for this guide is twofold. First, a conventional Trane that stops cooling is diagnosed by symptom and measurement — is there a call, is the contactor pulled in, is the capacitor in spec, is the charge right — which is exactly what the Service Facts flowcharts structure. Second, every 'Trane AC error code list' that assigns numbered or flash codes to these units has imported them from somewhere else: from the communicating platform's dealer alerts, from Trane's ductless lines, from Trane furnaces (which do have their own IFC flash codes, covered in the furnace hub), or from another brand entirely. Knowing that a table cannot exist for your unit is itself valuable information — it stops the code hunt and starts the real diagnosis.

Trane ductless: a complete code system, on a platform of its own

Trane's third AC platform is the one with the full code table: the single-zone high-wall inverter ductless systems (4MYW16 indoor / 4TYK16 outdoor), whose Trane service manual documents a complete display-code system — E-codes for failures (E0 indoor/outdoor communication, E1–E3 and E7/E8 sensors, E4 system abnormality, E5 model mismatch, E6 indoor fan, E9 IPM drive, EA/EU sensing-circuit faults, Eb display communication, EF outdoor fan, and EE, an EEPROM fault the manual's own two listings attribute to different units — flagged in the table rather than silently resolved) and P-codes for protections (P0 hardware module protection, P1 voltage, P2 current, P4 discharge temperature, P5–P8 thermal envelope protections, P9 software drive protection). Every row in this hub was checked against both of the manual's listings — its Section 9 display list and its Section 10 failure-code table — and codes appearing in only one listing (EC, EP, PA, and the remote-query F-family) were held back as unverified. The manual's behaviour notes matter as much as the codes: sensor faults clear themselves when the sensor reads normally again, outdoor-related codes can linger two minutes after recovery, and P0 is a fuse with a counter — six consecutive IPM protection stops convert it into E9, which latches until the unit is switched off and on, a design that tells you the drive problem is escalating whether or not anyone is watching. One cross-brand warning completes the platform picture: Trane also sells Gree-platform multi-split ductless systems whose wired-controller codes (E1 = high-pressure prevention there) flatly contradict this platform's E1 (room sensor) — Trane's own multi-split install manual publishes no malfunction table, so that system is documented in UNVERIFIED rather than tabulated. As with Carrier, the platform label is part of the code.

Less common and model-specific codes

Search data shows owners also meet these codes on Trane air conditioners: 126, 79. They are not part of the core code list Trane publishes for most models — several are series-specific, abbreviated display readings, or codes carried over from a sister platform — so we do not publish meanings for them rather than guess. Treat them by symptom: note what the machine was doing when the code appeared (filling, draining, heating, spinning), run one full power cycle (5 minutes off), and if the code returns, match the symptom to the closest documented family in the table above and check the tech sheet stored inside your machine for the model-specific definition.

Related guides

Facts on this page were checked against manufacturer documentation: manuals.plus · manuals.plus · www.delairteam.com · trane.com · www.trane.com · support.tranehome.com