B2322 – P-door motor electronic control unit(ECU) communication stop (Lexus)

Lexus-specific code — factory diagnostic data

B2322 means the Lexus CT200h has lost communication with the power door motor electronic control unit, so a door function may stop working or act intermittently. You may notice a power door feature that will not respond, or a door that works only sometimes. According to Lexus factory diagnostic data, this code indicates “P-door motor electronic control unit(ECU) communication stop.” The Main Body ECU sets this DTC when it expects messages or a response from the door motor ECU and does not receive them. This is a manufacturer-specific Lexus code, so the exact network path and module naming can vary by platform.

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B2322 Quick Answer

B2322 points to a communication loss between the Main Body ECU and the power door motor ECU on a Lexus CT200h. Diagnose it like a network or power/ground integrity fault before condemning any module.

What Does B2322 Mean?

Official definition: “P-door motor electronic control unit(ECU) communication stop.” In plain terms, the Main Body ECU cannot “talk” to the power door motor ECU, so the related power door operation may disable or become erratic. The code does not prove the door motor ECU failed. It only proves the Main Body ECU detected missing communication when it ran its checks.

What the module is checking: the Main Body ECU monitors expected communication activity from the door motor ECU. Depending on Lexus platform design, that communication may travel over a body network line or a dedicated serial link. Why it matters: communication stops for three common reasons: the door motor ECU loses power or ground, the network wiring loses integrity, or another network fault blocks message traffic. Your job is to confirm which condition exists with testing.

Theory of Operation

On Lexus body systems, the Main Body ECU coordinates many door-related functions. It commands outputs and requests status updates from “smart” door components. A power door motor ECU typically handles motor drive, position or jam logic, and self-protection. It then reports operating status back to the Main Body ECU so the body system can make decisions.

B2322 sets when that normal message exchange stops. The Main Body ECU expects to see the door motor ECU online during certain states, such as wake-up, unlock, or commanded door movement. If the door motor ECU goes offline due to a power or ground drop, or if the communication line opens, shorts, or becomes noisy, the Main Body ECU logs a communication stop. That breakdown changes diagnosis direction. You must prove the ECU lost power, lost ground, or lost signal integrity before replacing parts.

Symptoms

Communication-stop codes show up first in scan-tool behavior, then in the affected door feature.

• Scan tool shows the door motor ECU not responding, missing from the ECU list, or dropping out intermittently
• Power door function stops operating for the affected door feature controlled by the door motor ECU
• Intermittent operation where the feature works after cycling ignition or locking and unlocking
• Door response delay with sluggish or delayed reaction to switches or smart entry requests
• Body DTCs additional body network or door-related communication codes stored with B2322
• Noisy electrical behavior random body symptoms when the network wakes up, especially after battery service
• Security/lock interaction abnormal lock/unlock behavior tied to the door that contains the affected ECU

Common Causes

• P-door motor ECU not powered: A blown fuse, poor power distribution, or an ignition feed fault prevents the door motor ECU from waking up, so the Main body module reports a communication stop.
• High-resistance ground at the P-door motor ECU: Corrosion or a loose ground point drops voltage under load and resets the ECU, which breaks communication intermittently or constantly.
• Open or high resistance in the communication circuit: A partially broken wire, stretched harness, or poor splice increases resistance and the data signal cannot reach the Main body module.
• Short to ground or short to power on the communication line: Pinched wiring or water intrusion forces the line high or low and blocks normal message traffic.
• Connector terminal problems (spread, backed out, corrosion): A terminal that does not grip the pin or that has oxide on the contact causes a momentary disconnect that looks like an ECU drop-off.
• Harness damage at moving body points: Repeated flexing near hinges or pass-through boots can break conductors inside the insulation and create an intermittent communication stop.
• Low system voltage or unstable battery supply: A weak battery, charging issue, or high current draw event can pull voltage down and make the door ECU reboot and disappear from the network.
• Aftermarket accessory interference: Poorly tied-in alarms, remote starters, or add-on power door equipment can inject noise or load the circuit and disrupt module-to-module communication.
• P-door motor ECU internal fault: An internal ECU failure can stop message transmission, but you must prove power, ground, and circuit integrity first.

Diagnosis Steps

You need a scan tool that can perform a Lexus full network scan and display Body live data. Use a DVOM for voltage-drop testing under load. A back-probe kit and terminal inspection light help you catch pin-fit issues. Keep wiring diagrams available for the CT200h so you test the correct power, ground, and communication circuits.

1. Confirm the DTC and capture context: Check the Main body module for B2322 status (pending, confirmed/stored, or history). Record freeze frame data if available. For a communication-loss code, focus on ignition state, vehicle speed, battery voltage, and any related body/network DTCs. Freeze frame shows the conditions when the fault set.
2. Run a network scan and verify module presence: Perform a full system scan and note whether the P-door motor ECU appears in the network list. If the scan tool shows it as “not responding,” treat the fault as hard until proven otherwise. If it appears, treat the fault as intermittent and plan for harness movement testing and a road-test snapshot.
3. Check related DTCs first: Look for battery/voltage codes, main body communication codes, or other door-related ECU communication complaints. Grouped communication codes often point to a shared power feed, ground point, or splice. Clear nothing yet because you want to see what returns first.
4. Inspect fuses and power distribution before ECU testing: Check the body/door-related fuses and the power distribution points that supply the P-door motor ECU. Verify each fuse has proper feed on both sides with the circuit powered. Do not rely on visual fuse checks alone.
5. Verify ECU power and ground with voltage-drop under load: Access the P-door motor ECU connector and back-probe the power and ground circuits. Load the circuit by commanding the power door function on the scan tool or operating the system normally. Perform a ground voltage-drop test while the circuit operates. Keep ground drop under 0.1 V during operation. Also check power-side drop from the fuse output to the ECU feed while the system runs.
6. Inspect connectors and terminal fit: Disconnect the ECU connector and the Main body side connector(s) that carry the communication path, as applicable to the Lexus platform. Look for water tracks, green corrosion, overheated pins, and backed-out terminals. Perform a light drag test on suspect terminals to confirm pin tension. Correct terminal fit issues before any module replacement discussion.
7. Perform harness inspection at known flex and rub points: Inspect the harness routing through any door jamb boots, hinge areas, and body pass-throughs tied to the power door system. Flex the harness by hand while watching the scan tool for the ECU dropping on and off the network. If the code sets only during movement, you have a harness integrity problem even if the insulation looks fine.
8. Test communication circuit integrity with the correct key state: If the platform uses a dedicated communication line between the Main body and the P-door motor ECU, check for opens and shorts end-to-end with the connectors unplugged. If the platform uses a networked bus for this ECU, verify network health. Measure communication line bias voltage with ignition ON because bias does not exist with ignition OFF. If you see an abnormal fixed high or low reading, isolate by unplugging modules one at a time on that branch to find the shorted leg.
9. Use snapshot recording to catch intermittents: Freeze frame shows what happened when the DTC set. A scan-tool snapshot captures what happens during your test. Record a snapshot while commanding the power door function and while driving over bumps if the concern appears road induced. Watch battery voltage, module online/offline status, and command/feedback items for the power door system.
10. Confirm the repair: After repairing wiring, terminals, power/ground issues, or correcting an accessory problem, clear DTCs and repeat the same operating conditions. Confirm the P-door motor ECU stays present on the network scan. Verify B2322 does not return as pending or confirmed after multiple key cycles and normal use.

Professional tip: Treat B2322 as a “loss of message” indicator, not a failed ECU verdict. Prove the basics first. A door ECU that reboots from a ground drop often looks like a bad module, but voltage-drop testing under load exposes the real fault fast.

Possible Fixes

• Restore proper power feed: Repair the fuse supply, relay control, or power distribution fault that prevents the P-door motor ECU from powering up.
• Repair ground integrity: Clean and tighten the ECU ground point, repair ground wiring, and confirm less than 0.1 V drop under load.
• Repair communication circuit wiring: Fix opens, shorts to power, or shorts to ground on the communication line or network branch after isolating the affected segment.
• Service connector terminals: Remove corrosion, repair water intrusion, and replace damaged or loose terminals that cause intermittent disconnects.
• Correct harness routing and protection: Repair chafed sections and add proper retention so the harness does not rub or pinch during door movement.
• Remove or rework aftermarket accessories: Correct poor splices, shared grounds, or added loads that destabilize the circuit and interrupt communication.
• Replace the P-door motor ECU only after verification: Consider ECU replacement only after you prove stable power, stable ground, and a clean communication path with no dropouts.

Can I Still Drive With B2322?

You can usually drive a Lexus CT200h with B2322, because this code targets a body communication fault. It does not point to engine torque control. Still, treat any power door behavior as unpredictable. A power door may stop mid-travel, reverse, or refuse to close. Do not rely on it to latch. If the door does not latch, do not drive. Wind load can pull it open. If the scan shows other body or network codes, diagnose those first. A shared power or ground issue can expand quickly. Also avoid repeated door cycling until you test basics. Repeated stalls can overheat the motor or damage the drive.

How Serious Is This Code?

B2322 ranges from a nuisance to a safety concern, depending on what fails. If the only issue is a temporary communication drop, you may only see an inoperative power door feature. That falls under convenience. The risk rises when the door control loses position feedback or control while moving. Then the door may not fully latch, or it may stop in traffic areas. Communication loss can also signal a wiring fault in a flexing harness. That can worsen into shorts or repeated fuse blows. The code does not confirm a failed ECU. It flags that the main body module stopped receiving expected messages from the P-door motor ECU. You must confirm power, ground, and network integrity before you replace parts.

Common Misdiagnoses

Technicians often replace the power door motor or its ECU because the scan text names it. That wastes money when the real fault sits in the hinge-area harness or a loose connector. Another common miss involves battery support. Low system voltage during door operation can drop communication, then set B2322. Some shops also clear codes and stop testing after the door works once. Intermittent opens in a flex harness return under vibration. Others ignore the main body module’s role and skip checking related body DTCs. A shared CAN or LIN-style branch fault can take down several devices. Avoid guessing. Prove the failure with a communication check, a loaded power/ground test, and connector inspection under movement.

Most Likely Fix

The most common confirmed repair paths for B2322 involve restoring stable power, ground, or communication to the P-door motor ECU, not immediate module replacement. Start with the door-side and body-side connectors. Look for backed-out terminals, water intrusion, or fretting. Next, load-test the door ECU power and ground while commanding the door. Communication often drops when current rises and a weak ground lifts. If the scan tool cannot communicate with the door ECU while B2322 sets, focus on the network line continuity and connector tension. Consider ECU replacement only after you prove good power, ground, and bus integrity at the ECU pins, and the failure repeats.

Repair Costs

Network and communication fault repairs vary by root cause — wiring/connectors are often the source, but module-level repairs or replacements can be significantly more expensive.

Last updated: April 9, 2026

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