Diagnose the cause of an illuminated check engine light (fault indicator) on a 2025 Rivian EDV 500 dual motor electric delivery van using diagnostic tools and systematic troubleshooting procedures.

Warnings

Tools required

Parts

• Replacement sensor or component as identified × 1 — Varies based on diagnostic results

Preparation

1. Park vehicle on level ground and engage parking brake
2. Ensure vehicle is in Park mode and powered off
3. Allow high voltage system to enter safe mode (wait 5 minutes after power-off)
4. Verify 12V battery is in good condition and fully charged (low voltage can cause false fault codes)
5. Locate OBD-II diagnostic port under driver side dashboard area
6. Document any customer-reported symptoms, driving conditions when light appeared, and recent service history

Procedure

1. 1

   Connect diagnostic scanner and retrieve fault codes
   Connect the OBD-II scanner to the diagnostic port. Turn the vehicle to Accessory mode without entering Ready mode. Retrieve all stored Diagnostic Trouble Codes (DTCs) from all control modules including powertrain, battery management system, motor controllers, and chassis systems. Record all codes, freeze frame data, and pending codes. Note whether the check engine light is currently illuminated or stored as a history code.
2. 2

   Document and research retrieved codes
   Write down all fault codes with their descriptions. For Rivian-specific codes (typically P1xxx, P2xxx, B-codes, and U-codes), cross-reference with Rivian service bulletins and technical documentation. Prioritize codes by severity: Type A (emissions-related), Type B (system performance), and Type C (informational). Check for Technical Service Bulletins (TSBs) related to the specific codes retrieved.
3. 3

   Inspect high voltage system status
   Using the diagnostic scanner, check the status of the high voltage battery system, motor controllers, and DC-DC converter. Review battery pack temperature, state of charge, individual cell voltages, and isolation resistance values. Check for any high voltage system faults, contactor status irregularities, or thermal management issues. Verify the battery management system is reporting normal operation.
4. 4

   Check low voltage electrical system
   Use a digital multimeter to verify 12V battery voltage (should be 12.4-12.8V with vehicle off, 13.5-14.5V in Accessory mode). Inspect the DC-DC converter operation which maintains the 12V system. Check all major ground connections, particularly the battery negative terminal and chassis ground points. Low voltage can cause multiple spurious fault codes in electric vehicles.
5. 5

   Inspect motor and drivetrain sensors
   Visually inspect both front and rear motor assemblies for obvious damage, coolant leaks, or connector issues. Check motor temperature sensors, resolver position sensors, and motor controller connections. Inspect the front and rear differential speed sensors and associated wiring. Look for damaged harnesses, corroded connectors, or evidence of moisture intrusion at orange high voltage connections.
6. 6

   Review thermal management system
   Check the EV battery and motor cooling system operation. Inspect coolant levels in the battery thermal management system reservoir (should contain approximately 10 quarts of EV Battery/Motor Coolant). Check for coolant leaks around battery pack, motor heat exchangers, and cooling system hoses. Verify coolant pump operation and check for flow restrictions or air in the system that could cause overheating faults.
7. 7

   Test identified faulty components
   Based on the fault codes retrieved, perform targeted component testing. Use the multimeter to check resistance values, voltage supply, and ground integrity for suspected sensors. For example, if a motor temperature sensor code is present, check sensor resistance at ambient temperature and compare to specification. If a wheel speed sensor code is present, inspect the sensor air gap and tone ring condition.
8. 8

   Check communication network integrity
   Use the diagnostic scanner to verify CAN bus communication between all control modules. Check for U-codes indicating lost communication between modules. Inspect the CAN bus termination resistance (should read approximately 60 ohms between CAN-H and CAN-L with all modules connected). Look for damaged wiring, particularly in areas subject to flexing or exposed to road debris.
9. 9

   Perform active tests if applicable
   If the diagnostic tool supports bi-directional controls, perform active tests on suspected components. This may include commanding cooling pumps on/off, actuating contactors (with proper safety precautions), or checking motor controller responses. Monitor live data during these tests to identify intermittent faults or components that fail to respond correctly.
10. 10

    Road test with live data monitoring
    If safe and the fault allows vehicle operation, perform a controlled road test with the diagnostic scanner connected and monitoring live data. Attempt to replicate the conditions under which the fault occurred. Monitor motor torque requests, battery current flow, thermal system operation, and regenerative braking function. Watch for the check engine light to illuminate and note any correlation with specific driving conditions.
11. 11

    Clear codes and verify repair
    Once the root cause has been identified and repaired (sensor replaced, connector cleaned, wiring repaired, software updated, etc.), clear all fault codes from all modules. Cycle the vehicle through multiple power cycles. Perform another road test to ensure the fault does not return. If codes return immediately, further diagnosis is required. Allow the vehicle to complete at least one full drive cycle to verify all monitors have run.

Reassembly

1. Reconnect any sensors or connectors that were disconnected during diagnosis
2. Ensure all high voltage connector locking mechanisms are fully engaged
3. Reinstall any trim panels or covers removed for access
4. Verify 12V battery connections are tight and secure

Verification

• Confirm all diagnostic trouble codes have been cleared and do not return
• Verify the check engine light extinguishes after the vehicle completes a drive cycle
• Check that all vehicle systems are functioning normally with no warning lights
• Review all diagnostic monitors to confirm they show 'Ready' or 'Complete' status
• Test drive the vehicle under various conditions (acceleration, regenerative braking, highway speed) to ensure no faults return
• Provide the customer with a detailed explanation of the fault found, repair performed, and any recommended follow-up service

More procedures for this vehicle