I recently investigated the P1604 engine code on Toyota vehicles, which indicates a startability fault. This means that the engine struggles to start or stutters as soon as it is ignited. After conducting research in various sources and Toyota owners’ complaints, I found that the issue is typically linked with fuel delivery, ignition, or engine sensor malfunction.
What I Found about the Toyota P1604 Code
The P1604 code appears when the engine speed is below 500 RPM when cranking or when the engine cranks but the speed drops to 200 RPM or below within 2 seconds. This tells me that the problem could be with the fuel system, ignition system, or even the engine control module (ECM).
What Happens When This Code Appears?
According to what I have noticed, most people with this issue have:
Difficulty in starting the car or lots of cranking time
The engine stalling when attempting to start
Rough idling or misfires after starting
The check engine light illumination
Loss of engine power
How to Fix the Toyota P1604 Code
What Triggers the P1604 Code?
After reading through different cases, I found several reasons why this code appears:
Starter issues – A faulty or weak starter can cause the engine not to turn over.
Crankshaft or camshaft position sensor failure – These sensors help to regulate timing, and when they fail, the engine will not start properly.
Malfunctions of the fuel system – A clogged fuel filter, low fuel pump, or defective fuel injectors can result in this issue.
Ignition system failure – Faulty spark plugs, faulty ignition coils, or wiring damage may prevent proper combustion.
Battery or alternator failure – Low voltage can affect engine cranking.
Air intake malfunction – A dirty throttle body or faulty MAF sensor can cause the engine to stall.
ECM failure – In extreme cases, the engine control module itself could be defective.
From different reports and repair guides, here are the most common repairs:
Check the battery – A weak battery can cause difficult starts, so voltage checking is a good beginning.
Check the starter motor – If the starter is experiencing problems, it should be replaced.
Check for additional trouble codes – Scanning for other codes may pinpoint the difficulty.
Check the fuel system – Replacing the fuel filter, fuel pump diagnosis, and injector cleaning may alleviate the problem.
Check the ignition system – If the spark plugs or ignition coils are worn out, changing them might fix the issue.
Throttle body & MAF sensor cleaning – A dirty throttle body will cause the engine to stall.
Reset the ECM – Clearing the code and resetting the system might be sufficient to clean up the issue.