The Toyota P1604 Error – Potential Causes And Solutions

Is the code P1604 showing up on your scanning tool after getting your Toyota vehicle scanned? Although your car may be seemingly fine at first glance, the P1604 code signifies that your car has an underlying problem. And, of course, you should do what you can to resolve this code as soon as possible.

That said, you don’t have to worry if you don’t consider yourself a car expert. After all, this guide will walk you through everything you need to know about the P1604 code and how to resolve it below.

Meaning of Toyota Code P1604

The P1604 code appears if your car engine malfunctions when attempting to start it. The said code also appears if your car engine takes a while to start. Another possible reason for the code’s appearance is if your car engine ends up stalling right after starting it.

All engine components must be working correctly to start your engine successfully. Therefore, any resulting defect in any of its components will lead to a startability failure. However, this code will also appear if you performed troubleshooting on your vehicle while it was low on fuel.

Signs Your Car Has the P1604 Code

Based on the definition above, the P1604 code primarily appears if your car’s engine refuses to start at all. However, it may also appear if your vehicle is experiencing the following problems as well:

  • Your car engine takes a while to start
  • Your car’s check engine light is lit up
  • Your car engine performs poorly
  • Your car engine experiences ignition misfires or engine stalls

That said, if your car ticks some or all of the signs above, it’s a clear indication that your Toyota car has the P1604 code. Here are the possible reasons why your engine has this code below.

Possible Reasons Why Code P1604 is Showing Up

If you’re looking for the possible cause of your vehicle’s P1604 code, here are some possible reasons why the code is showing up below:

1. Your engine ran out of fuel

As stated above, the mentioned code doesn’t always appear due to engine startability failure. The code may also be stored on your engine if you started it while running low or out of fuel. Make sure that your engine has plenty of fuel before troubleshooting your car.

2. Your car battery has a low charge

The battery is one of the first parts you should inspect in your car after receiving the said code. After all, the battery is in charge of supplying electricity to the starter motor. If the battery has a low charge, it will be unable to start your engine.

A dead or low-charged battery is the result of a failing alternator. It might also be due to an issue in the battery’s charging system.

3. Your car’s starting system is malfunctioning

A vehicle’s starting system consists of the following vital parts:

  • Ignition Switch
  • Neutral Safety Switch
  • Battery
  • Connecting Wires
  • Starter Relay
  • Starter Motor

Any defect in any of the mentioned parts can lead to a malfunctioning starting system, which is another possible reason for the appearance of the P1604 code.

4. Your vehicle’s fuel filter is obstructed

An obstructed fuel filter is another culprit of the P1604 code. Besides, this component is responsible for filtering out any impurities in fuel before transporting it to your car’s engine. However, fuel filters eventually get obstructed.

Once that happens, the fuel pressure gets significantly reduced. This affects the amount of fuel being carried to the engine’s combustion chamber, resulting in your engine’s startability failure.

5. Your vehicle’s ECM is defective

Although least likely, the Engine Control Module or the ECM is another likely cause for the code. ECMs primarily get damaged due to a surge in power or if it suffers a short circuit. Once the ECM gets damaged for any of the said reasons, the combination of air and fuel in your engine might not reach adequate levels. As expected, this also leads to engine startup failures.

6. Your car is using low-grade fuel

The fuel you’re using might also be one of the reasons why the P1604 code showed up on your system. Low-grade fuel contains a lot of debris and particles, which are known for damaging spark plugs and clogging your injectors. Once these parts get damaged, you will need to change them to resolve your engine startup issues. You’ll want to switch your fuel as well to avoid this scenario again.

How to Resolve the P1604 Code?

Like always, resolving this code requires determining the root cause of your problem first. Based on the possible reasons for the code’s appearance in your system, you should thoroughly inspect the following parts:

  • Battery: Check the battery for a possible disconnection or a low charge. Don’t forget to check if its terminals and the interior of your connectors are clean as well.
  • Fuel System: Ensure that its fuel filters aren’t obstructed with impurities. Double-check as well if its pump is functioning accordingly.
  • Starting System: Inspect the wirings and components of your starting system. If possible, determine if the system is receiving the appropriate voltage.
  • ECM: Check if your ECM’s wires are corroded. Corroded wires are responsible for reducing conductivity, which is likely a reason why your car received the startability failure code.

As stated above, your fuel could also be contributing to the destruction of your car’s components. If that’s the case, you should immediately switch the type of fuel you’re using. Make sure you’re only using high-quality fuel for your car if you want to prevent encountering the P1604 code again.

You should also avoid troubleshooting your car while it’s running low on fuel. Again, the code may also appear in your system if you troubleshoot it on an empty tank. However, if the P1604 code is still showing up in your scans despite checking all your engine components and replacing your fuel, it’s best to have your vehicle checked by a professional.

I Deleted the P1604 Code. Can I Still Have My Car Checked?

Are you worried that you can’t take your car to your local repair shop since you deleted the code? Whether you deleted it intentionally or by accident, there’s nothing to worry about. Your technician can still view the P1604 code through the engine’s code history. So, rest assured that they can still conduct a proper diagnosis of your vehicle.


The P1604 code showing up in your Toyota car is an indication that your car engine has startup problems. The code appears for various reasons, so you’ll have to do a thorough car inspection to determine the root cause. Finally, if all else fails, it’s best to have your car taken to a professional to resolve the code.

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