MajorVery commonEngine

Lexus IS: IS250 4GR-FSE intake valve carbon build-up (direct injection, no port injectors)

IS250 4GR-FSE intake valve carbon build-up (direct injection, no port injectors) is a very common engine fault on the Lexus IS on the 2005–2015 cars, and we rate it major. Putting it right costs $900 to $1,800 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 41 documented faults on the Lexus IS.

Vehicle: Lexus IS
Engine: 4GR-FSE
Years: 2005–2015
Fuel: petrol
System: Engine

This page covers the Lexus IS as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Lexus IS faults41 documented faults on this model

What you are looking at

What goes wrong

The IS250's 4GR-FSE V6 is direct-injection only — unlike the IS350's dual-injection 2GR-FSE, no fuel ever washes over the intake valves, so carbon builds up on them relentlessly. By 100,000-150,000 km this causes cold-start misfires, rough idle, hesitation and noticeable power loss. Lexus ran a customer support programme in some markets involving chemical cleaning, but the proper fix is a walnut-shell blast of the intake ports, and the problem returns every 80,000-100,000 km or so. This applies to both the XE20 (2005-2013) and the carry-over IS250 in the early XE30 (2013-2015).

What you would notice

Rough idle or misfire when cold
Hesitation or flat spots on acceleration
Check engine light with misfire codes (P0300-P0306)
Sluggish performance versus expectations

How to check it

Where to look. Intake manifold and intake valves, top of the V6 engine

Cold-start the car (feel the bonnet first to make sure the seller hasn't pre-warmed it) and let it idle — watch the tacho for uneven idle and listen for stumbles.
Ask a mechanic to check for stored misfire codes.
Ask for proof of a walnut blast or induction clean and when it was done.

Parts involved: Fuel injector.

What it costs to put right

$900 to $1,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the intake ever been walnut-blasted or decarbonised, and is there an invoice?”
“Does it ever misfire or idle rough on cold mornings?”

Now check the Lexus IS you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

ClubLexus IS 2nd-gen forum: 'IS250 Walnut Blasting Valves DIY' (thread 822505)
Lexus Owners Club UK: 'IS250 carbon build-up - Oh yes!' (topic 138528)
Torque News: 'Lexus IS250 GS300 carbon build-up — what you need to know'

Lexus IS buyer questions

Is is250 4gr-fse intake valve carbon build-up (direct injection, no port injectors) serious on a Lexus IS?

We rate it major and very common on the Lexus IS. The IS250's 4GR-FSE V6 is direct-injection only — unlike the IS350's dual-injection 2GR-FSE, no fuel ever washes over the intake valves, so carbon builds up on them relentlessly. By 100,000-150,000 km this causes cold-start misfires, rough idle, hesitation and noticeable power loss. Lexus ran a customer support programme in some markets involving chemical cleaning, but the proper fix is a walnut-shell blast of the intake ports, and the problem returns every 80,000-100,000 km or so. This applies to both the XE20 (2005-2013) and the carry-over IS250 in the early XE30 (2013-2015).

How much does it cost to fix on a Lexus IS?

$900 to $1,800 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Lexus IS years are affected?

Our research records this fault on the 2005–2015 Lexus IS. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Cold-start the car (feel the bonnet first to make sure the seller hasn't pre-warmed it) and let it idle — watch the tacho for uneven idle and listen for stumbles. Ask a mechanic to check for stored misfire codes. Ask for proof of a walnut blast or induction clean and when it was done. Look here: Intake manifold and intake valves, top of the V6 engine