IsItAGoodCar
Reliability Guide

Common Problems with the
2012 Toyota iQ (AJ10)

We've identified 2 known issues that can affect the 2012 Toyota iQ (AJ10). None are considered critical, but they're worth knowing about before you buy.

2
Known Issues
0
Serious
2
Moderate
0
Minor

All Known Issues

1.0 1KR-FE EGR Valve Carbon Clogging and Engine Stalling

ModerateEngine

Urban-driven 1.0-litre three-cylinder models suffer from heavy soot and carbon buildup within the exhaust gas recirculation (EGR) valve and intake manifold channels. Persistent short urban trips prevent the engine from reaching self-cleaning temperatures, causing the valve pintle to stick open. This introduces unmetered exhaust gas into the intake charge at low rpm, causing rough hunting idle, jerking under light throttle, and unexpected engine stalling when stopping at junctions.

Est. Repair Cost: £150–£350
Warning Signs:

Engine stumbles, hunts, or stalls completely when dipping the clutch and slowing to a halt, Erratic idle speed fluctuating wildly between 500 and 1,100 rpm when stationary, Check engine warning light illuminated on the dashboard with fault code P0400, Hesitation and momentary stuttering when gently pressing the accelerator from rest

What to Inspect:
  • Allow the vehicle to idle for five minutes following a warm test drive and verify idle speed remains solid at 800 rpm
  • Drive at low speeds in second gear, dipping the clutch suddenly to ensure the engine recovers smoothly without stalling
  • Check service invoices for previous EGR valve cleaning or replacement by a franchised dealer
Verified by IsItAGoodCar Research TeamUpdated

Multidrive CVT Automatic Transmission Judder on Take-Off

ModerateGearbox & Transmission

The optional Multidrive continuously variable transmission (CVT) can develop a noticeable shudder and hesitation when setting off from a standstill, particularly on upward gradients. The fault stems from degraded CVT fluid, contaminated solenoid valves within the hydraulic valve body, or slippage of the steel drive belt across the variable pulleys due to missed fluid changes.

Est. Repair Cost: £250–£750
Warning Signs:

Pronounced vibrating judder transmitted through the driver seat and floorpan when pulling away gently, Hesitation of several seconds followed by sudden harsh lurch when pressing the accelerator pedal, Whining noise from the transmission casing that increases with road speed in town driving, Transmission flares revs without corresponding vehicle acceleration on hills

What to Inspect:
  • Conduct several gentle and brisk pull-aways from a dead stop on an incline to check for belt judder
  • Select Reverse on a slope and ensure immediate smooth engagement without delay or thumping
  • Review service history receipts for genuine Toyota CVT Fluid TC or FE changes
Verified by IsItAGoodCar Research TeamUpdated

Buying Tips for 2012 Toyota iQ (AJ10)

  • Test the idle stability of the 1.0-litre engine to ensure the EGR valve is not choked with carbon from repetitive short urban trips.
  • Turn the steering wheel lock-to-lock at low speed to confirm the electric power steering motor assists smoothly without knocking.
  • On Multidrive CVT models, execute smooth low-speed pull-aways on an incline to check for transmission belt shudder or clutch slip.
  • Inspect front brake discs for heavy rust ridges, as lightweight urban cars rarely work their friction brakes hard enough to clear corrosion.
  • Check the operation of the passenger-side dashboard sliding glove bag and fold-flat rear seats to ensure interior clips remain intact.
Check a 2012 Toyota iQ (AJ10) by Registration