C1E2E – Request control ACCAebaxTar invalid (BYD)

C1E2E means your BYD Dolphin may temporarily limit or disable a chassis control function related to an ACC request, which can change how the car behaves during driver-assistance operation. In plain terms, the vehicle is seeing a control request it considers “not valid,” so it may ignore it to stay safe. On BYD vehicles this is a manufacturer-specific code, and the exact logic behind what is considered “invalid” can vary by platform and software version. The official BYD description is “Request control ACCAebaxTar invalid,” which should be treated as the working definition for diagnosis.

C1E2E Quick Answer

On BYD vehicles, C1E2E indicates an invalid control request related to “ACCAebaxTar,” so the chassis control system may reject that request and reduce or suspend the affected assistance/control feature until the issue is resolved.

What Does C1E2E Mean?

C1E2E means the BYD chassis control system detected a request to control “ACCAebaxTar” that does not meet validity checks, so it flags the request as invalid and may not act on it. In more technical terms (using the scan tool’s definition as the source of truth), the controller supervising chassis functions is receiving or generating a command request whose state, range, timing, or message integrity fails internal plausibility rules for “Request control ACCAebaxTar,” leading to a manufacturer-specific DTC being stored.

Theory of Operation

On BYD platforms, chassis-related controllers commonly rely on request/acknowledge logic between modules: one module requests a target or control action, and another module validates that request before executing it. Validity checks typically include message freshness, correct addressing, compatible operating mode, and plausibility with other inputs (for example, the vehicle’s current driver-assistance state).

With C1E2E, the key point is not that a specific actuator has failed, but that the “Request control ACCAebaxTar” request is being judged invalid. Depending on BYD architecture, this can be caused by an upstream module sending a malformed or out-of-context request, a network issue that corrupts or delays the message, or a local controller state that makes the request unacceptable (such as mismatched mode, missing prerequisite signals, or internal software/logic faults).

Symptoms

You may notice one or more of the following on a BYD Dolphin when C1E2E is present:

• Scan tool shows C1E2E stored in chassis-related diagnostics and may show the related request status toggling between valid/invalid in live data
• Driver assistance feature (commonly ACC-related functions, depending on configuration) may be unavailable, limited, or cancel unexpectedly
• Warning message a driver-assistance or chassis control warning may appear, or a system status message may indicate a feature is temporarily unavailable
• Intermittent behavior the issue may come and go with key cycles, temperature, or after driving a short distance
• Reduced control the vehicle may refuse certain automated control actions because the request is not accepted
• Fail-safe the system may default to a safer degraded mode until the request becomes valid again
• Multiple DTCs related communication/plausibility codes may appear alongside C1E2E depending on which prerequisite signals are missing

Common Causes

• Invalid or out-of-range request/command message for ACCAebaxTar being generated by a BYD chassis control function (request does not meet expected format, state, or plausibility)
• CAN/LIN network integrity issue affecting request validation (intermittent open, short-to-ground/short-to-power, high resistance, poor shielding, or water intrusion in network wiring)
• Connector fault at a chassis-related control module involved in request generation/validation (loose terminals, backed-out pins, corrosion, damaged seals)
• Power supply disturbance to one or more chassis ECUs (low system voltage event, weak 12V battery condition, poor power distribution connection, voltage drop across a fuse/relay/junction)
• Ground quality problem (ground offset, high resistance ground point, loose fastener) causing a module to misinterpret or mis-transmit a request
• Software/calibration mismatch or corrupted configuration within a BYD chassis module causing the request to be flagged as invalid (platform-dependent; verify with BYD service information)
• Module internal fault in the ECU that sends or validates the ACCAebaxTar request (failure to encode/decode messages correctly under certain conditions)
• Aftermarket device or retrofit wiring interfering with chassis network traffic or power distribution (telematics trackers, dashcams hardwired to ignition circuits, non-OE splices)

Diagnosis Steps

Tools you’ll typically need: a scan tool capable of full BYD chassis module access (network scan, live data, actuation tests), a DVOM, a test light or load tool for power/ground checks, and basic back-probing tools. If available, use an oscilloscope for network waveform integrity checks. Use BYD wiring diagrams and connector views for the Dolphin (2020) platform where possible.

1. Confirm the DTC is present as C1E2E – Request control ACCAebaxTar invalid and record freeze-frame/event data (conditions when set, related DTCs, and which module logged it if the scan tool provides that detail). Clear codes and perform a short road test or functional run to see if C1E2E resets immediately or intermittently.
2. Before any ECU pin measurements, perform quick triage: check for obvious harness damage in chassis/underbody areas and verify fuses and power distribution feeding chassis control modules. If your scan tool supports it, run a full module/network scan and note whether any expected chassis ECUs are missing or intermittently offline (a missing module can cause “invalid request” flags in other modules).
3. Verify ECU power and ground quality under load for the module(s) implicated by the scan report (or the chassis domain controller if BYD groups functions). Use a DVOM and a load method (test light/load tool) to check for voltage drop on B+ and ground circuits while the system is awake; don’t rely on open-circuit readings alone.
4. Inspect connectors and harness routing for the chassis control network and related modules: disconnect and check for corrosion, water ingress, pin fit/terminal spread, backed-out pins, and damage at strain points. Re-seat connectors fully and ensure any connector locks are properly engaged.
5. With the scan tool, review live data and status parameters relevant to the request validation (names vary by platform). Look for flags such as “request valid/invalid,” “control request source,” “mode status,” or plausibility indicators. Compare the moment the request flips invalid with other observations (voltage, wake/sleep state, communication dropouts).
6. Perform functional tests/actuation (if supported) for the chassis function that is associated with the request path (platform-dependent). The goal is to see whether the system can command the function and whether the receiving module acknowledges it, or whether the request is rejected as invalid. Stop the test if warnings indicate reduced braking/steering stability or other safety risk.
7. If network integrity is suspect, perform communication circuit checks per BYD wiring: verify continuity and check for shorts between network lines and to power/ground. If you measure network line bias voltages, do so with ignition ON and the vehicle awake; ignition-off readings are not a valid reference because network biasing may be inactive. If available, use a scope to look for noise, missing transitions, or intermittent dropouts while manipulating the harness gently.
8. Check for power/ground disturbances that can corrupt messaging: monitor system voltage and chassis ECU supply during key-on, READY transitions, and during loads (lights, HVAC blower, steering/brake actuation if safe). Investigate any sudden dips or unstable readings by tracing back through fuses, relays, junctions, and ground points.
9. Look for configuration/software issues: review scan tool identification data (part numbers, software versions, configuration status) for chassis modules involved in sending/validating the request. If BYD service information indicates an update, reprogramming, or configuration alignment is required to correct “invalid request” behavior, perform that only after confirming stable power and network integrity.
10. After repairs, clear DTCs and repeat the enabling conditions: run a network scan, recheck live data validity flags, and road test under similar conditions to the freeze frame. Confirm C1E2E does not return and that no new chassis/communication codes appear.

Professional tip: An “invalid request” DTC on BYD chassis systems is often a symptom rather than a single failed part. Treat it like a plausibility/validation problem: confirm which module originates the request and which module rejects it, then prove power/ground stability and network integrity first. Only after the electrical foundation is verified should you consider software/configuration or module replacement.

Possible Fixes

• Repair or replace damaged wiring/terminals/connectors affecting the chassis control request path (including CAN/LIN network wiring) and ensure proper connector seating and terminal tension
• Restore proper power distribution to chassis ECUs (replace blown fuse, repair poor junction connection, correct relay/feed issue) and address any underlying cause of recurring fuse faults
• Clean/repair ground points and correct high-resistance grounds causing module resets or message corruption
• Remove or rewire aftermarket devices that interfere with chassis power or network circuits
• Perform BYD-approved software update, configuration alignment, or re-initialization for affected chassis modules when service information indicates it can correct request validation faults
• Replace the confirmed faulty module involved in generating or validating the ACCAebaxTar request only after verifying all related power/ground/network circuits and performing required coding/initialization steps

Can I Still Drive With C1E2E?

You can often still drive a 2020 BYD Dolphin with DTC C1E2E stored, but you should treat it as a chassis-control concern because the official definition is “Request control ACCAebaxTar invalid.” In practical terms, a control request being judged invalid can lead to reduced or blocked operation of the feature that depends on that request, or the system may revert to a default/fail-safe state. If you notice any unexpected behavior tied to chassis functions (such as a driver-assist function not engaging, warnings, or altered stability/traction behavior), drive cautiously, avoid aggressive maneuvers, and plan diagnosis soon. If warning messages escalate or the vehicle feels unstable, stop driving and have it inspected.

How Serious Is This Code?

C1E2E is usually “medium seriousness” because it indicates a control request is invalid rather than clearly identifying a failed sensor or actuator. It may be mostly an inconvenience when it only disables a related control function or triggers warning messages without changing vehicle behavior. It becomes more serious if the chassis system enters a protective mode that limits assistance functions, or if the invalid request is caused by unstable power/ground, network communication errors, or a module reset—conditions that can create intermittent, hard-to-predict behavior. Treat it as a safety-relevant issue if you also have stability/assist warnings, multiple chassis DTCs, or symptoms that appear during braking, turning, or low-traction driving.

Common Misdiagnoses

Technicians commonly misdiagnose C1E2E by replacing a sensor or actuator simply because the complaint mentions a driver-assist or chassis feature, even though the code text points to an invalid “request control” rather than a specific component failure. Another frequent mistake is ignoring network and power integrity: low voltage events, poor grounds, or connector fretting can corrupt messages and make a legitimate request appear “invalid.” It’s also easy to chase the wrong module when the scan report doesn’t name the source module; instead, confirm which BYD controller is logging C1E2E and review its live data and related codes. Avoid wasted spending by checking for accompanying U-codes, verifying battery/charging stability, inspecting connectors for water intrusion, and confirming the request’s status in live data before replacing parts.

Most Likely Fix

The most commonly confirmed repair directions for an “invalid request control” code on BYD platforms are (1) restoring reliable power/ground and connector integrity to the chassis-related controller that stores C1E2E and to the module providing the request (clean/secure terminals, correct pin fit, repair corrosion or water ingress, and confirm stable module wake/sleep behavior), and (2) correcting communication/data validity problems (repair harness issues, address related communication DTCs, and confirm the request message/state becomes valid in live data after repairs). If the issue remains after wiring and network integrity checks, a software update or module configuration issue may be involved on some BYD variants, but that should only be pursued after proving inputs, outputs, and communication health.

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: March 29, 2026