The P1605 code means your Toyota’s engine speed dropped below 400 RPM while running. In simple terms, the engine almost stalled—or actually did. This can happen for a lot of reasons, but the most common? Running out of fuel or a problem with air-fuel delivery.
If you’ve got this code, don’t panic. Here’s how to troubleshoot and fix it.
What Are the Signs of P1605?
You might notice:
Rough idle – The engine feels unstable or shaky.
Stalling – The engine cuts out suddenly.
Hard to restart – It cranks but takes time to start.
Weak acceleration – Feels sluggish when pressing the gas.
Check Engine Light ON – The ECU recorded the issue.
Possible Causes and Fixes
1. Fuel Issues (Most Common)
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Ran out of fuel? – It happens! If the tank was too low, the engine stalled.
Fix: Add fuel and reset the code. -
Fuel pump issue? – A weak or failing fuel pump won’t send enough fuel.
Fix: Listen for the pump’s humming sound when turning the key. No sound? Could be bad. -
Dirty fuel injectors? – Clogged fuel injectors can mess up the fuel supply.
Fix: Use injector cleaner or replace if needed.
2. Air Intake Problems
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Air leak in the intake? – If air is escaping, the engine runs rough.
Fix: Check for cracked hoses or loose connections. -
Dirty MAF sensor? – The Mass Air Flow (MAF) sensor might be giving wrong readings.
Fix: Clean it with MAF cleaner spray. -
Throttle body dirty? – Carbon buildup can block airflow, messing with idle.
Fix: Clean the throttle body with throttle cleaner.
3. Ignition & Sensor Problems
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Bad spark plugs or ignition coils? – Weak spark = weak combustion = RPM drop.
Fix: Check and replace worn spark plugs or coils. -
Coolant temperature sensor faulty? – If it sends bad data, the fuel mix is wrong.
Fix: Replace the sensor if readings are off.
4. Other Possible Causes
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EGR Valve stuck? – A bad Exhaust Gas Recirculation (EGR) valve can affect idle.
Fix: Clean or replace it. -
Power steering or A/C overload? – Too much load on the engine can drag RPMs down.
Fix: See if the stalling happens when steering or turning on the A/C.
If your Toyota has P1605, check the fuel first. Then move on to air intake, ignition, and sensors. Most of the time, it’s something simple—low fuel, dirty injectors, or a clogged throttle body.
Fix the issue, reset the code, and you’re good to go!
