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Tundra · Diagnostic readout

Toyota Tundra Check Engine Light: Common Causes, Codes & Fixes

What it isThe Tundra's computer logged a fault — on the 5.7L V8, secondary air injection (AIR) is a known one
SeverityModerate
Safe to drive?Steady light: OK short-term — hold off towing/hauling. Flashing: stop — active misfire
Typical cost$0 gas cap to $1,000+ AIR pump

Fix it

  1. Scan the code first

    OBD2 reader or free parts-store scan — it names the system at fault.

  2. Check the gas cap

    Tighten until it clicks; replace a cracked seal. Cheapest, most common trigger.

  3. Repair what the code points to

    O2/air-fuel sensor, plugs/coils for a misfire, or the AIR switching valve on a P2440-series.

  4. Clear it and confirm

    Clear the code with the scanner and check the light stays off over a few drives.

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What's going on

On a Tundra the check engine light means the engine computer logged a trouble code. Steady = a stored fault to diagnose within a few days; flashing = an active misfire that dumps raw fuel into the exhaust, so ease off and protect the converters.

Usual triggers: a loose gas cap (EVAP), an aging oxygen / air-fuel sensor past ~100k, an ignition misfire from V8 plugs or coils, a MAF / vacuum leak, and the Tundra’s signature — secondary air injection (AIR) faults on the 5.7L V8 (P2440/P2441/P2442, valve sticks or corrodes). Read the code first.

Steady light: drive normally but hold off on heavy towing or hauling until diagnosed — a misfire or sensor fault worsens under load. Flashing: stop driving hard. See the check engine light overview and the common codes list.

Related codes

P0300P0171P2440P2441

FAQ

What are the most common check engine light causes on a Toyota Tundra?
A loose gas cap, oxygen/air-fuel sensors, ignition coils or spark plugs causing a misfire, and on the 5.7L V8 the secondary air injection (AIR) system. Reading the code tells you which to chase first.
What is the secondary air injection code on a Tundra?
Many Tundras log P2440/P2441/P2442 for the secondary air injection (AIR) switching valve or pump, which can stick or corrode. It's emissions-related; the truck still runs, but it should be repaired to pass inspection and clear the light.
Is it safe to drive my Tundra with the check engine light on?
A steady light is usually fine for short, normal driving. Avoid heavy towing or hauling until you know the cause, and stop driving hard if the light is flashing — that's an active misfire.
Will the check engine light reset itself on a Tundra?
If the fault was temporary, such as a loose gas cap, the light can clear after several drive cycles. A stored fault needs to be repaired and the code cleared with a scanner.