Let’s talk about something that has been coming up more and more in messages and conversations: Steering Assistance Loss, or EPS issues on the GR Yaris.
The car uses an electric power steering system (column-mounted assist motor). There’s no hydraulic pump, no fluid, no traditional rack assist. Everything is electronic, torque-based, and software-controlled.
And like most modern EPS systems, when something feels “wrong”, the cause is not always what people assume.
Over time, I’ve seen the reports fall into three clear categories. Let’s go through them properly, so if you encounter this issue, you will be able to make a correct diagnosis.
Pro note: at the end of this blog post you will find the product codes for EPS Column replacement. As you may appreciate, Toyota has already gone thru a number of iterative revisions, and has a new code for the Gen 2 GR Yaris: I'm curious to see if the issue has been fixed on the new vehicles!!
1. Temporary Loss of Assist on Track
This is probably the most common scenario.
You’re pushing hard. High grip tires. Repeated heavy cornering. Long session.
Then suddenly — mid-corner — steering goes heavier.
It doesn’t lock. It doesn’t fail completely.
It just feels like assist dropped.
Then later, it comes back.
This is almost always thermal derating.
EPS motors generate heat under high torque demand. On track — especially with wider tires or more aggressive alignment — steering load increases significantly. The system protects itself by reducing assist when temperatures rise.
That reduction feels dramatic, especially mid-corner.
Important:
If the assist returns after cooling down and no warning lights remain, this is very likely protection logic — not failure.
2. “Power Steering Malfunction – Steering Power Low”
This is a different situation.
If you see a warning message and assist becomes intermittent during normal driving, that’s not just track derating.
Now you’re looking at one of three things:
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Voltage supply issue
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Sensor plausibility problem
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EPS column assembly fault
Before replacing anything, you must rule out voltage.
EPS draws significant current. If the 12V battery is weak or charging voltage isn’t stable, the EPS module can throw warnings or reduce assist.
I’ve seen cases where replacing the battery solved everything.
Never jump straight to replacing the steering column.
3. Noises When Steering
This one creates the most confusion.
People hear:
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A whine
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A light mechanical sound
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A click
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A subtle vibration in the wheel
Let’s separate things clearly.
Normal EPS Sound
Electric assist motors do make noise.
Especially at low speed or while stationary.
A mild whine is not automatically a defect.
Direction-Specific Noise (Only Steering Right, for example)
If the noise only happens in one direction, I immediately suspect mechanical asymmetry before EPS failure.
Common causes:
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Top mount binding (especially with coilovers)
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Camber plates under load
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Spring seating issues
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Alignment differences left vs right
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Increased caster loading one side differently
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Tie rod end or rack joint play
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CV joint if noise appears while moving
If EPS motor or reduction gear were failing internally, noise would normally occur in both directions, not exclusively one.
4. The Voltage Factor (Seriously Important)
Modern EPS systems are voltage sensitive.
If you have:
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Random warnings
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Assist coming and going
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Symptoms worse at idle
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Steering changes when electrical load increases
Check battery health and charging voltage under load.
Do this before doing anything else.
5. When It’s Actually the EPS Column
If:
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Warning persists
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Assist fails repeatedly
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DTCs point to torque sensor or motor fault
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Voltage checks out
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Mechanical inspection is clean
Then yes — you may be looking at EPS column replacement.
Toyota has used different part numbers depending on build period. If you go down that road, match by VIN and production date.
But again — this is not the first thing I would assume.
6. How I Would Diagnose It Step by Step
If this was my car in the workshop:
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Check battery health properly (not just static voltage).
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Check charging voltage at idle and during steering input.
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Reproduce the issue stationary and while rolling.
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Inspect suspension geometry and top mounts if modified.
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Scan EPS module with a proper tool (not a generic OBD reader).
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Only then consider component replacement.
Simple logic, structured approach.
7. The Important Distinction
Most GR Yaris EPS “problems” fall into:
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Track-related thermal derate
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Voltage sensitivity
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Mechanical noise misdiagnosed as EPS
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Genuine but less common column assembly faults
Understanding which category you’re in prevents unnecessary parts replacement.
Final Thoughts
The GR Yaris steering system is generally reliable. When something feels wrong, it’s usually one of:
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Overload
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Heat
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Voltage
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Or mechanical modification side-effects
Very rarely is it a sudden catastrophic EPS failure without warning.
If you’re experiencing something specific, describe it precisely:
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Stationary or moving?
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Only one direction?
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Warning light or not?
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Stock suspension or modified?
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At what steering angle?
The details matter.
And as always — diagnose calmly, not emotionally!
If you need to order a new EPS column assembly, keep in mind the following:
Gen 1 GR Yaris (GXPA16 – 2020 to early 2024)
LHD (Europe) – Column Sub-Assembly EPS
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4520A-52340
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4520A-52350
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4520A-52380
These part numbers vary depending on:
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Production batch
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VIN range
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Market specification
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Minor internal revisions
Toyota supersessions may apply, meaning older numbers can be replaced by updated ones in the system.
Gen 2 GR Yaris (Facelift – 2024 onwards)
LHD (Europe) – Column Sub-Assembly EPS
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4520A-52620
This corresponds to the revised steering column assembly introduced with the updated model.
Important Notes
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These are complete EPS column assemblies, not individual motor or sensor components.
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Always confirm by:
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VIN number
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Production date
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Market specification (LHD vs RHD)
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Toyota often revises internal components without changing external fitment, so supersession is common.
If you want, I can now break down:
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Whether Gen 2 EPS is mechanically interchangeable with Gen 1
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What actually changed between revisions
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Or how to confirm if your unit is early or updated version without removing it.