Toyota Prius Check Engine Light Diagnosis

Toyota Prius Check Engine Light Diagnosis (2007- 2017 Toyota Prius Check Engine Light)

Last updated on January 13th, 2023 at 08:29 pm

Whenever your vehicle displays the “Check Engine” Light, you should know that your vehicle has had engine problems or maybe just a loose gas cap.

It is true that a lot of car owners misunderstand this, note that the check engine light message can mean many different things.

Sometimes it could be a broken oxygen sensor, a misfiring engine, or even simply a loose gas cap.

Anytime you see the check engine light, most time it doesn’t mean you should pull your car over the other side of the road and call a tow truck.

What it means is you should get the car examined by a professional immediately. Once you ignore this warning sign, you could end up causing more harm to your car.

Read these also: Easy Guide on How to Disable Check Engine Light Permanently

Common Toyota Prius check engine light codes to Note

Whenever someone sees the warning light illuminated in Prius, it sometimes sends panic, not knowing what has happened to the car.

Below are Common Toyota Prius check engine light codes and fixes that are not guesses, but proven repairs for your Prius.

#1. P0A93 Inverter Cooling System Performance Code

This error code is quite common, and the repair is very easy to handle. Although the service manual says it could be caused by several things, but it has been proven that it is just to change the electric inverter water pump.

#2. P0420 Catalyst System Efficiency Below Threshold

In case you have had your cat converter stolen before, this is the code that would appear along with a droning noise, it will inform you that a part of your exhaust is missing.

#3. P1121 Coolant Flow Control Valve Position Sensor Stuck

One other check engine light list of failures and common code is the P1121 code. What this code means is to change the three-way coolant valve.

The P1121 code is something that appears on Prius frequently. Once the coolant valve gets stuck, what you need to do is change it along with some coolant.

#4. P0A80/P3000 Replace Hybrid Battery Code

The P0A80 code can occur for a lot of reasons; this code is informing you that your hybrid battery is not working as it should. 

#5. C1256 Failed Brake Actuator Code

The C1256 code simply means you need to change your brake actuator on your Prius car.

There is a reason this occurs, it tells you that the brake system can no longer maintain the pressure internally. 

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What to do when Toyota Prius check engine light flashing

Indeed, low oil pressure or even an overheating engine can trigger the check engine light to illuminate, your dashboard also has other lights and gauges that warns you once there is serious issues.

You are advised to read your owner’s manual to study various reasons that could trigger the check engine light.

Doing this will give you a tour of other gauge and warning indicators on your dashboard.

When your check engine light illuminates, the first thing to do is examine any serious issue that needs immediate attention.

Examine your dashboard gauges and their lights for any indications of low oil pressure or overheating. If this happens, it means you should pull over your car and shut down the engine. 

The next thing to do is, try tightening your gas cap. Sometimes this could solve the problem.

Try to reduce your speed and, if possible, reduce the weight you’re carrying. Then have your car inspected immediately to prevent expensive damage. Why Prius Won’t Turn Off & How to Turn It Off

How to 2007 to 2009 Prius check engine light reset

  • First turn off your car
  • Insert your key to the ignition
  • You can now hold down your brake and press the power button to turn the car on.
  • Now continue to hold down the brake, and then press the ODO trip button. (Note that the ODO button is located by the hazard lights.)
  • Now turn your car off while you still hold the ODO button and brake.
  • And while you still press both the brake and ODO, now press the power button to turn your car on again.
  • Once this is done, the ODO meter will display dashed lines and will count down
  • Once these dashes get to the right, your odometer will flash 000000. After that, it will turn back on and the lights will be reset.

How to: 2014 Toyota Prius check engine light reset (Applicable reset tips for 2010 to 2017)

Make use of A Scanning Tool

Making use of a scanning tool is the easiest method for checking engine light reset. In case you are wondering how to 2014 Toyota Prius check engine light reset, here are 3 steps for you.

Step 1: Try connecting the scanning tool to the OBD – II

You can connect the scanning tool to the OBD- II (Onboard diagnostic connector) which is under your steering column.

You can now turn the ignition switch ON and please don’t forget to turn off all your car gadgets.

Step 2: Viewing error codes by just pressing the “READ” button

You should press the “READ” button on the scanning tool to see the error codes of your engine. Make sure you write down the error code, write in the order you received them for future repairs or reference.

Step 3: Now remove the error code

You should press the “ERASE” button on the scanning tool to finally remove the error code. Once done, the Check Engine Light will turn off if all error codes are cleared.

 Why Toyota Prius won’t start making weird noise

In case you are hearing a weird noise, it might be a battery or alternator issue.

Hearing a weird noise whenever you are trying to start up your car could mean that there is something wrong with your electrical system.

It could be that your battery is dead, or even your alternator, which charges your car battery, isn’t working well.

However, in case the source of the noise is electrical, then it could be from the starter, maybe it doesn’t have enough juice to remain powered. 

If this is the case, a misfiring starter is just a symptom of the issue and not the cause. However, you need to blame your vehicle’s electrical system, then a jumpstart might get your car moving again temporarily.

Note that once your car starts running, contact a technician to examine every part of the electrical system.

Or maybe your alternator or battery needs to be replaced. But sometimes the solution could be to remove corrosion from the battery cables to help strengthen the battery’s charge.

Why Toyota Prius won’t start check engine light

Sometimes there are various reasons why your Prius won’t start. Below are some of the most common problems that cause a vehicle not to crank:

1. Your Battery Cables

Most time while your battery cables are not the most likely problem to cause your Prius not to start, they are some of the easiest to diagnose.

2. Your Battery Charge

Once your car battery no longer has enough charging power to turn the starter ON, your Prius car will not start. Remember that as your battery ages, its “cranking amps” decreases; it will leave it with a diminished capacity for starting the vehicle.

3. Your Car Starter

One of the things to worry about whenever your Prius isn’t starting would be the car starter itself. Once the car starter isn’t working well, it will be impossible to start the vehicle (except it’s a manual car, then you can pop start it). 

Why Toyota Prius makes noise when turned off

This is a little pump that will circulate coolant from your car cylinder head into an insulated container. Remember, your car hot coolant job is to warm up the cylinder head any time the engine is started. It is also good for the head due to heat soak after a shutdown which causes head temp to go up significantly in some other engines.

However, this helps your engine to reach operating temperature much faster and therefore cleans the emissions sooner (Because a cold engine pollutes much more than an engine that is at a normal operating temperature). So it is good when it makes noise turned off.

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