Why is my Lexus GX 460 in limp mode with 4LO flashing and the check engine light on?

Short answer: On 2010–2013 GX 460s, a check engine light with 4LO flashing, VSC and TRAC off and the engine in limp mode is very often the secondary air injection system. It's a pump and two valves that push fresh air into the exhaust on cold starts to cut emissions. Water and debris ruin the valves and pump. Lexus covers this under a special service campaign, and owners reported it has no year or mileage limit. Owners have had it fixed free.

Symptom: Check engine light, flashing 4LO light, VSC and TRAC warnings, and reduced power. Codes P2440, P2441, P2442 or P2445 are common.

What to check first

1. Have the codes read. P2440, P2441, P2442 and P2445 point to the air injection system.
2. Call a Lexus dealer and ask about the air injection service campaign for your VIN.
3. To get out of limp mode for now, owners clear the codes with a scanner. It may come back.
4. Get it booked. Owners said the repair takes a few hours.

Likely causes

1. Stuck or failed air switching valves. Covered under the Lexus campaign for these years.
2. Failed air injection pump or its filter. Replaced under the campaign if damaged.

What it usually costs

Under the Lexus campaign, owners on ClubLexus had it done free. One said the repair would have been over $2,000 otherwise.

Is it safe to keep driving?

It drives, but with less power and the stability and traction systems may be off. Be careful on slippery roads and when merging, and get it fixed. Verify with a mechanic or dealer.

DIY or shop?

Dealer. It's covered under the Lexus campaign.

Recalls, bulletins and complaints in plain words

• Lexus special service campaign (secondary air injection, 2010–2013 GX 460): Lexus replaces the air pump filter and both switching valves, and the pump if it's damaged. Owners on ClubLexus said the coverage was updated to have no year or mileage limit. This is a campaign, not a safety recall, so ask a Lexus dealer to check your VIN.
• NHTSA complaints: 11 keyword-matched complaints for Lexus GX 460 2010–2013 (of 92 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-20; keywords: air (injection, pump), secondary air, limp, check engine, 4lo, vsc, trac) (NHTSA returned no complaint data for 4 model-year queries).

What owners report

• In #SAIP - Service Campaign (#JLG) '10-'13 / Update: No mileage or year restrictions (page 44) on ClubLexus, owners said clearing the codes gets the truck out of limp mode for a while, that the repair would run over $2,000, that P2441 was covered too, and that their repair was done free.
• In 2010-2013 Special Service Campaign on ClubLexus, owners described the campaign: the air pump filter and both switching valves replaced, the pump replaced if damaged, no year or mileage limit, and a few hours at the dealer. They noted an earlier version of the coverage had time and mileage limits.

My take

My advice as a former lot tech: every 2010–2013 GX that came through, I called the dealer with the VIN. This campaign is free, and it saves a buyer a big bill.

Vehicle focus: 2010–2013 Lexus GX 460.

Safety / mechanic note

Limp mode cuts power and the stability control may be off. Verify with a mechanic.