erwincrystal4
Alphard ECU Error
Summary of the thread
A 2018 Toyota Alphard experienced reduced engine power and a check engine light, with diagnostics indicating an ECU-related error. Potential causes included a faulty sensor or a defective main relay supplying power to the ECU. The suggested solution was to test and possibly replace the main relay, which was confirmed as the issue. After replacing the defective relay, the vehicle's performance returned to normal.
Did this summary help you solve your problem?
4 comment(s)
erwincrystal4 (community.author)
A faulty relay makes sense, actually. Where exactly is the main relay located, and how can I test it to see if it's the culprit before I start thinking about replacing the whole ECU?
isabella_mystic1
The main relay's location can vary, but it's often in the engine bay's fuse box, sometimes under the dash. Check your owner's manual for its exact location and diagram. Testing involves checking for voltage at the relay and verifying it clicks when energized. If unsure, a workshop can pinpoint it quickly. Given the ECU error, it's best to have it professionally diagnosed.
erwincrystal4 (community.author)
Thanks so much! I followed your advice and had a workshop take a look. Turns out the main relay was defective! They replaced it, cleared the error codes, and the Alphard is running perfectly again. Total cost was only 120€. I really appreciate your help pointing me in the right direction!
rmh_community_comment_box_header
community_crosslink_scanner_headline
community_crosslink_scanner_intro
community_crosslink_scanner_title
community_crosslink_scanner_price
community_crosslink_rmh_headline
community_crosslink_rmh_intro
community_crosslink_rmh_title
community_crosslink_rmh_subtitle
community_crosslink_rmh_brand
TOYOTA
community_crosslink_rmh_model
ALPHARD
isabella_mystic1
Reduced power and an ECU error? Sounds like it could be a few things, but the ECU itself is a prime suspect. Could be a faulty sensor feeding it bad data, or the ECU itself might be on the fritz. Have you checked the main relay that supplies power to the ECU? A defective relay can cause intermittent issues and throw those kinds of errors. Easy and cheap to test/replace before diving deeper.