Chassis, generic

C05D6 Power Steering Control Module Processor Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

The electric power steering controller has found that its own processor, or the cross-check between its processors, is not working as expected. Toyota documents the code as C05D604 in the ECU of the EPS steering gear: 2019–2020 RAV4 and RAV4 Hybrid light the EPS warning in red or yellow at start-up or while driving (T-SB-0061-20), and the 2022 Tundra and Lexus LX 600 log it at start-up, often together with C15D704. In each case the fix is reprogramming the gear ECU with revised logic. Many EPS units pair a main and a monitoring microcontroller that must both enable the motor relay; Mando describes such a start-up check. If the self-test fails, assist is reduced or switched off, so steering becomes heavy.

Likely causes

EPS controller software flags a false processor fault, update available
Supply voltage dip during engine start disturbs the self-test
Internal hardware fault in the steering control module

Symptoms

  • Red or yellow power steering warning lamp
  • Steering suddenly heavier or assist reduced
  • Fault appears mainly right after starting the vehicle

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–2,500
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

eps module

Related codes

U0131C05D5

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, patents.google.com.