C2122 – Data from transmitter ID 2 not received (main) (Lexus)

Lexus-specific code — factory diagnostic data

C2122 means the Lexus CT200h tire pressure system cannot “hear” one of the stored tire pressure transmitters, so the TPMS warning can turn on and pressure data may stop updating. You can still drive in most cases, but you lose reliable low-tire warnings, which is a real safety issue. According to Lexus factory diagnostic data, this code indicates: “Data from transmitter ID 2 not received (main).” This is a manufacturer-specific chassis code. Its exact logic can vary by Lexus platform, so you must diagnose it using the scan tool description and TPMS data, not by guessing a bad sensor.

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C2122 Quick Answer

C2122 sets when the tire pressure monitor does not receive the expected RF data from the transmitter stored as “ID 2” in the main set. The most common causes are a dead or missing sensor, an ID registration issue, or a reception problem.

What Does C2122 Mean?

Official definition: “Data from transmitter ID 2 not received (main).” In plain terms, the Lexus tire pressure monitor expects a specific sensor to report, but that sensor’s message never arrives. In practice, the TPMS light may stay on, and one tire’s pressure may show dashes or fail to update, depending on how the scan tool displays TPMS data.

What the module actually checks: the tire pressure monitor (TPMS ECU) tracks a list of learned transmitter IDs for the “main” set. It listens for RF transmissions that match those IDs within an expected time window and operating conditions. Why that matters: C2122 does not prove the sensor failed. The code only points you toward a “not received” condition, so you must confirm whether the ID exists, the system can receive RF, and the sensor can transmit.

Theory of Operation

Under normal conditions, each wheel-mounted TPMS transmitter measures pressure and temperature. It sends RF messages that include its unique ID. The Lexus CT200h tire pressure monitor receives those RF messages and compares the IDs to the stored “main” ID set.

C2122 sets when the monitor does not receive messages that match the stored ID 2 entry. The breakdown can come from the transmitter side, the learned ID list, or the receiver side. A wheel swap, incorrect ID registration, shielded reception, or electrical power issues at the monitor can all produce the same “not received” result.

Symptoms

You will usually notice a TPMS warning and missing data for one learned transmitter entry.

• Scan tool behavior TPMS Data List shows one transmitter not updating, missing, or flagged “no reception” for the main set
• TPMS light Warning lamp stays on or returns shortly after clearing codes
• Pressure display One tire reading shows dashes, blanks, or freezes while others update
• Intermittent fault Warning appears after driving, then disappears after a key cycle or temperature change
• After tire service Code appears after rotation, tire replacement, wheel swap, or sensor service
• Relearn failure ID registration completes but the same ID 2 still shows no reception
• Multiple TPMS codes C2122 may appear with other “transmitter not received” codes if reception drops out

Common Causes

• TPMS transmitter ID 2 not transmitting: The tire pressure sensor assigned as “ID 2” stops sending a usable RF message, so the tire pressure monitor never receives that ID’s data.
• Transmitter ID mismatch or wrong ID registered: The tire pressure monitor looks for a specific coded ID, and it flags C2122 when the stored ID 2 does not match the sensor actually installed.
• Incorrect main/secondary set selection: If the Lexus CT200h uses multiple registered sets, the monitor can set C2122 when it listens to the wrong “main” set for ID 2.
• RF signal blocked or heavily attenuated: A wheel location, aftermarket wheel construction, corrosion at the valve area, or external interference can weaken the RF path enough that the module misses the ID 2 packets.
• TPMS warning valve/sensor physically damaged: Impact damage, a bent valve stem, or internal sensor damage can prevent stable data transmission for the stored ID 2.
• Tire pressure monitor ECU power or ground issue: Low supply voltage or a high-resistance ground can reduce receiver sensitivity and processing, which leads to “not received” faults for a single ID.
• Connector or harness concern at the tire pressure monitor: Corrosion, loose terminals, or water intrusion at the monitor connector can interrupt RF receiver operation or module logic.
• Receiver/antenna circuit fault (platform dependent): Some Lexus platforms use separate receiver paths or antenna circuits, and a fault in that path can prevent reliable reception of one transmitter’s messages.

Diagnosis Steps

Use a capable scan tool that reads Lexus TPMS data and performs ID registration or set selection. Have a DVOM for voltage-drop testing, a test light, and basic back-probing tools. A TPMS activation tool helps, but the CT200h may still require a drive to update some data. Pull wiring diagrams and connector views before pin testing.

1. Confirm C2122 in the tire pressure monitor and record freeze frame. Note ignition state, vehicle speed, battery voltage, and any related TPMS DTCs. Freeze frame shows the exact conditions when the monitor stopped receiving “transmitter ID 2” on the main set.
2. Perform a full health check/network scan and verify the tire pressure monitor appears on the scan tool. If the module drops offline, treat that as a power/ground or network problem first. If the module stays online, continue with ID reception diagnostics.
3. Check fuses and power distribution feeding the tire pressure monitor before probing the ECU. Load-test the suspected fuse circuits with a test light, not just a visual check. A fuse can look good and still fail under load from heat damage.
4. Verify tire pressure monitor power and ground under load using voltage-drop testing. Run the system in a state where the module stays awake, then measure ground drop from module ground pin to battery negative. Keep ground drop below 0.1 V with the circuit operating, and correct any higher drop before chasing sensors.
5. Use the scan tool to review TPMS Data List items related to ID reception. Look for “main” set status, registered IDs, and any “ID 2” receive counters, last-received time, or signal status fields. If “ID 2” never updates while others do, treat it as an ID-specific reception issue, not a system-wide failure.
6. Verify the vehicle’s registered IDs match the sensors installed. Compare the ID labeled on the sensor (if accessible) or use a TPMS tool to read the sensor’s ID over RF. If the stored “ID 2” does not match any sensor on the vehicle, correct registration or set selection before replacing parts.
7. Confirm the monitor listens to the correct set and mode. If the CT200h supports a main/secondary set, command the correct set selection with the scan tool or follow the Lexus procedure. Recheck live data after switching, because C2122 specifically states “not received (main).”
8. Inspect the physical condition of the wheel/tire assemblies and the valve areas. Look for evidence of impact, sealant use, corrosion, or incorrect sensor installation. Also verify no metal objects or aftermarket components sit near the receiver area that could block RF.
9. Try to force an update to isolate an intermittent problem. If you have a TPMS activation tool, trigger the suspected transmitter and watch for an ID update in live data. If the platform requires driving, perform a controlled drive while watching the data list, and capture a scan tool snapshot when the fault occurs. Freeze frame tells you when it set; a snapshot helps catch the moment it fails.
10. If ID mismatch and set selection check out, evaluate whether the problem follows the wheel. Swap the suspected wheel/sensor with another wheel position only if Lexus service information allows it and you can maintain safety. Then verify whether the “not received” condition follows the sensor or stays tied to “ID 2” in the module’s registration list.
11. Clear DTCs and perform a verification drive or relearn procedure. Recheck for pending vs stored status after the monitor runs. A hard fault often returns quickly, while an intermittent reception issue may take time and specific speed conditions to reset C2122.

Professional tip: Treat C2122 as a “suspected trouble area” code, not a parts verdict. Lexus TPMS faults often come from an ID registration or set-selection mistake after tire service. Prove reception failure with live data before you disturb tires or install sensors. When voltage-drop tests fail, fix power and ground first, because a weak module can “lose” only one ID under marginal RF conditions.

Possible Fixes

• Correct the registered transmitter IDs and confirm the tire pressure monitor uses the correct “main” set.
• Repair power or ground faults to the tire pressure monitor, including cleaning and tightening ground points after voltage-drop testing.
• Repair connector or harness issues at the tire pressure monitor, including terminal tension correction and water-intrusion remediation.
• Replace the TPMS transmitter that fails functional activation or will not report its ID consistently, after verifying registration and module integrity.
• Remove RF interference sources or correct installation issues that block the transmitter signal, then confirm reception with live data.
• Replace the tire pressure monitor ECU only after you prove good power/ground, correct IDs, and continued inability to receive known-good transmitter data.

Can I Still Drive With C2122?

You can usually drive your Lexus CT200h with C2122, but you should treat it as a safety-system warning. This code means the tire pressure monitor did not receive data from transmitter ID 2 on the “main” set. The car will still move normally, but TPMS warning behavior can change. You may lose accurate low-pressure alerts for one tire. Check all four tire pressures with a quality gauge before driving. If any tire repeatedly loses pressure, stop and repair the tire. Do not rely on TPMS while C2122 remains active.

How Serious Is This Code?

C2122 ranges from an inconvenience to a real safety concern. It becomes “mostly inconvenient” when all tires hold correct pressure and the TPMS just cannot “see” one transmitter ID. It becomes a safety issue when you cannot trust the system to warn you about a rapid leak. High speeds, heavy loads, and wet roads raise the risk. This code does not create a drivability fault by itself. However, it removes a layer of protection that Lexus designed into the chassis safety package. Fix it promptly if the warning stays on.

Common Misdiagnoses

Technicians often replace a sensor immediately because the code mentions “transmitter ID 2.” That wastes money when the real problem involves registration, the wrong wheel set, or the “main” ID list not matching the sensors installed. Another common miss involves low sensor wake-up opportunity. A car that sits, or a sensor with marginal battery, may not transmit often. Shops also skip basic checks of TPMS ECU power, ground integrity, and connector fit. Confirm the ID list, confirm receiver activity, and confirm wiring integrity before you condemn any sensor or module.

Most Likely Fix

The most frequent confirmed repair directions for C2122 on a Lexus CT200h involve correcting a transmitter ID mismatch in the “main” set and restoring valid sensor transmission. Start by verifying the sensor IDs stored in the tire pressure monitor match the sensors installed. Then confirm the suspect wheel sensor transmits and wakes up during a drive. If the ID matches but the module still misses data, focus on sensor condition, valve-stem damage, or a weak internal battery. Only after those checks should you consider TPMS ECU wiring faults or ECU issues.

Repair Costs

Repair cost depends on whether the confirmed root cause is wiring, connector condition, a sensor, a module, or the labor needed to diagnose the fault correctly.

Last updated: April 8, 2026

Definition source: Lexus factory description · Autel MaxiSys Ultra & EV. Diagnostic guidance is based on factory-defined fault logic for this code.