Fix it
- Check the fuel tank and the cap
Toyota's manuals ask two questions first: is the tank empty, and is the cap loose? Fix either and the light should go off after several driving trips.
- Write down the code and the message
Note the exact wording on the screen (Check Engine, Hybrid System Malfunction, Check Hybrid System) and whether the red triangle is lit. Record it before anyone clears it.
- 2010–2015 Prius or 2012–2017 Prius v: ask about 23TE02 and 23TE03
Inverter codes P0A94, P0A1A, P324E, P3004, P0A7A or P0A78 fall under Toyota programs that run 20 years from first use with no mileage limit. Have a Toyota dealer check the VIN.
- Run the VIN for recalls
At nhtsa.gov/recalls. Inverter recalls 14V-053, 18V-684 and 20V-369, water pump recall 12V-536 (2004–2009) and hybrid software recall 21V-734 (2022). Each covers certain cars only, so check the VIN.
- Mind the 40-drive rule
Toyota's manuals say the stored code is not cleared until the car has been driven 40 or more times, even after the light goes out.
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On a Prius, the check engine light covers the hybrid system as well as the engine. Toyota’s 2010 owner’s manual (p.497) lists four systems behind the malfunction indicator lamp, including “The electronic hybrid system control system”. The 2017 (p.653) and 2023 (p.464) manuals put the hybrid system first and close the entry with one instruction: “Have the vehicle inspected by your Toyota dealer immediately.”
The messages that appear with it get the same answer. The 2017 manual (p.666) lists “Hybrid System Malfunction”, Check Engine and “Hybrid Battery System Malfunction” among those that call for an immediate dealer inspection, and the 2023 manual (p.477) agrees. One message is more urgent. For “Braking Power Low Stop in a Safe Place See Owner’s Manual”, the 2017 book says to “Immediately stop the vehicle in a safe place and contact your Toyota dealer”.
A light that blinks rather than staying on has its own page.
First: the tank and the cap
The 2017 (p.658) and 2023 (p.471) manuals ask two questions first: is the fuel tank empty, and is the cap loose? Fill the tank or tighten the cap. The 2010 manual (p.501) adds that “The light will go off after taking several driving trips”. Still on after several trips? Contact a Toyota dealer as soon as possible.
The code outlasts the light. All three manuals (2010 p.415, 2017 p.583, 2023 p.409) say a loose cap turns the lamp on as a temporary malfunction, and the error code isn’t cleared until the car has been driven 40 or more times. The 2010 book warns that with the cap loose, the car may not pass the I/M test.
The red triangle
Owners often describe a red triangle beside the check engine light. That’s the master warning light. According to the 2010 manual (p.508), it comes on or flashes to show that a message is “currently being displayed on the multi-information display”. So the triangle sends you to the screen: read the message, and write it down with the code.
2010–2015 Prius and 2012–2017 Prius v: 20 years of inverter coverage
Start here if your car is a 2010–2015 liftback or a 2012–2017 Prius v. Toyota’s Customer Confidence Programs 23TE02 and 23TE03, part of the Prius inverter class action settlement, were first published to dealers on February 16, 2023. They cover certain 2010–2015 Prius (about 918,000 cars) and certain 2012–2017 Prius v (about 170,000). The part is the Intelligent Power Module (IPM) inside the inverter.
- 23TE03 covers IPM failure “indicated by hybrid system diagnostic trouble codes (DTCs): P0A94, P0A1A, P324E,” and/or P3004, codes “that your dealer can find by the use of Techstream”, Toyota’s diagnostic tool. With any of them set, the letter says, warning lamps light up and the car “will enter Fail Safe Mode”.
- 23TE02 covers P0A7A or P0A78, or IPM thermal damage “regardless of what DTC is detected”.
Both run 20 years, with “no mileage limitation from the date of first use (DOFU)”.
To use them:
- Go to an authorized Toyota dealer. The coverage runs through them only.
- Ask for the hybrid codes to be read and the VIN checked against 23TE02 and 23TE03.
- Check the title. Cars branded salvage, total loss, true mileage unknown or similar are not eligible.
- If the dealer says no, it must give you the appeal wording. The appeal goes in within 45 days, through www.toyotapriusinvertersettlement.com, the site Toyota’s letter names.
Earlier programs on the same part: ZE3 (2014, 2010–2014 Prius) and 20TE10 (2020, 2013–2015 Prius, 2014–2017 Prius v).
The inverter recalls. Have the VIN checked for each:
- 14V-053 (2010–2014 Prius, from March 21, 2014): IPM transistors “may become damaged from high operating temperatures”, and then “various warning lamps will be illuminated on the instrument panel and the vehicle will have reduced power”. Software update; an inverter that failed first is repaired or replaced at no charge.
- 18V-684 (2010–2014 Prius, 2012–2014 Prius v, from January 22, 2019): excess IPM voltage may “cause the hybrid system to shut down”. The software is needed even on cars updated under 14V-053 or 15V-449 (a 2012–2014 Prius v recall).
- 20V-369: the same condition on 2013–2015 Prius and 2014–2017 Prius v that 18V-684 left out. A failed inverter is repaired or replaced before the update, free.
Of 70 light complaints on 2010–2015 liftbacks, 22 describe a Check Hybrid System message with it, 12 name the inverter, the IPM or P0A94, and 11 cite one of these recalls. A 2010 owner (ODI 11458033) saw the check engine light; “Less than one minute later” came the Check Hybrid System alert, and “The vehicle instantly had no power”.
Codes Toyota’s documents connect to the light
| Code | Prius years in the document | Toyota document |
|---|---|---|
| P0A94, P0A1A, P324E, P3004 | 2010–2015 (Prius v 2012–2017) | Program 23TE03 |
| P0A7A, P0A78 | 2010–2015 (Prius v 2012–2017) | Program 23TE02 |
| P0401 | 2010–2012 (Prius v 2012) | Program ZF3 |
| P0300 to P0304 | 2010–2015 | T-SB-0116-15, T-SB-0147-16 |
| P0A0F | 2010–2013 (Prius v 2012–2013) | T-SB-0041-15 |
| P148F00 | 2016–2019 | T-SB-0135-19 |
| P0A80, P0A7F | 2004–2009, later years too | T-SB-0153-13, T-SB-0074-20 |
| P1121 | 2004–2005 | Bulletin 02405 |
| P3190, P3191, P3101 | 2001–2002 | Bulletin 01202 |
Codes for other Toyotas are on our code list.
The complaint file, by generation
NHTSA holds 12,510 complaints for the Prius liftback, and 201 of them mention the light. The Prius v adds 479 more, 27 of which mention it.
| Model years | Mention the light | All complaints |
|---|---|---|
| 2001–2003 (1st gen) | 14 | 431 |
| 2004–2009 (2nd gen) | 107 | 7,102 |
| 2010–2015 (3rd gen) | 70 | 4,553 |
| 2016–2022 (4th gen) | 9 | 357 |
| 2023–2025 (5th gen) | 1 | 63 |
These are unverified owner reports, and a count is not a failure rate. Generations that sold more, or are older, collect more complaints of every kind. Our check engine light by model study scales by sales instead and puts the Prius liftback at 2.30 per 100,000 sold, eighth of nine models.
2001–2003: first generation
Fourteen of 431 complaints mention the light. NHTSA keeps summaries of two Toyota bulletins. Bulletin 01202 (2001–2002) covers the master, hybrid and malfunction indicator lamp “warning light on with diagnostic trouble code P3190, P3191 and P3101”. Bulletin 01703 (2001) covers the light with P0420 “due to an ECM software logic error”. Program ZTI for those hybrid codes ended September 30, 2019, per its dealer package. Recall 06V-266 (2001–2002) replaces a crankshaft position sensor whose connector can take in oil, which “could cause the engine to stall while driving and not be able to be restarted”.
2004–2009: second generation
Of 7,102 complaints, 107 mention the light.
Shutdowns on 2004–2005 cars. Of 56 light complaints on 2004–2005 cars (1,661 in all), at least 36, checked by hand, describe the gasoline engine stopping or the car losing power, usually with the red triangle and other lights on. Several crawled along on electric power. One 2004 shut down at 40 mph, “all dashboard warning lights became illuminated”, and the dealer found P3191 (ODI 10123842). NHTSA’s summary of Toyota’s Special Service Campaign 50P (record 0522, October 2005) reads “to reprogram the ECM system which may cause some or all of the warning lights to illuminate”: master, hybrid system, engine, vehicle stability control and brake. Bulletin 04704 (October 2004) covers the check engine and master warning lights coming on “after slowing down and stopping” and when trying to restart.
Inverter water pump, recall 12V-536. More than a dozen complaints name the hybrid (inverter) water pump; a 2008 owner’s code read “P0A93 - COOLANT INVERTER PUMP FAILING” (ODI 11343344). Recall 12V-536 covers certain 2004–2009 Prius built August 6, 2003, through March 30, 2009. A scratch may have occurred inside the electric water pump at the coil wire, the wire may corrode, and a short circuit could follow, “creating a stall-like condition of the hybrid system”. The pump is replaced free (recall began January 17, 2013).
P1121. Eight complaints on 2005–2009 cars name P1121 or the coolant flow control valve, such as a 2009 with the code “indicating a problem with the coolant control valve” (ODI 10595823). Toyota’s bulletin 02405 (May 19, 2005, for 2004–2005 Prius) is summarized as MIL ON DTC P1121.
Brake actuator. Seven complaints name it (ODI 11650664, a 2007 with C1256 and C1300). Toyota’s T-SB-0032-16 Rev1 (April 18, 2017) covers brake and ABS warning lights with C1252, C1253, C1256 or C1391 on 2004–2009 Prius; T-SB-0174-12 Rev covers the check engine and ABS/VSC lights with C1247.
HV battery cooling fan. T-SB-0153-13 Rev2 ties the light with P0A80 or P0A7F on 2004–2009 cars to “dust or debris buildup in the HV battery cooling fan”, under the “Toyota Hybrid System Warranty … 96 months or 100,000 miles”. Later fan bulletins name the same codes: T-SB-0013-14 Rev (2013–2015 Prius, P0A80), T-SB-0171-13 Rev (2012–2014 Prius v, P0A80/P0A7F) and T-SB-0074-20 (August 5, 2020), which spans 2003–2020 Prius, Prius c and Prius v.
2010–2015: third generation, beyond the inverter
Seventy of 4,553 liftback complaints mention the light. Beyond the inverter, here is what Toyota’s paperwork covers.
The EGR valve (program ZF3). Warranty Enhancement Program ZF3 (policy bulletin POL16-04, June 16, 2016, revised August 30, 2019) covers certain 2010–2012 Prius, 2012 Prius v and 2010–2012 Prius Plug-in for “a rough idle and/or rattle noise from the transaxle at cold start due to a sticking” EGR valve. In that case “the vehicle may illuminate the check engine light and set diagnostic trouble” code P0401. Primary coverage ran “until March 31, 2017, regardless of mileage”, then 10 years from first use or 150,000 miles, whichever came first. For cars first sold in 2010–2012, that window is likely over; check by VIN. Only 3 of the 70 light complaints mention the EGR: a 2011 with a sticking valve (ODI 11403571), a 2010 owner quoting the ZF3 letter (ODI 10948013), and a 2014 owner who says the EGR was moderately clogged with carbon (ODI 11471272).
Misfire bulletins. In T-SB-0116-15 Rev1, some 2010–2015 Prius may run rough or set the light with P0300 through P0304 during light acceleration “while the Exhaust Gas Recirculation (EGR) system is active”; the repair is “Replace the Intake Manifold assembly”. T-SB-0147-16 (October 14, 2016) covers some 2013–2015 Prius and Prius PHV and 2013–2016 Prius v with rough idle or a “tapping noise from the HV transaxle at cold start”, the light and the same codes. Its fix is an ECM reprogram, under the Federal Emission Warranty (“96 months or 80,000 miles”).
Head gaskets (owner reports only). Four 2010–2015 liftback owners and six 2012–2014 Prius v owners say a failed head gasket was diagnosed after the light came on. One 2012 owner says the car “now needs new engine due to blown head gasket” (ODI 11319578); a 2012 Prius v owner was told of “coolant in the combustion chamber due to a failed head gasket” (ODI 11292147). We found no Toyota document about head gaskets on these cars in NHTSA’s file, and the ZF3 papers and misfire bulletins don’t mention one. These are owners’ accounts.
Brakes. Thirteen liftback complaints name the brake booster, the booster pump, the accumulator or C1391 along with the light, such as “C1391 (Antilock Brake System - abnormal leak in accumulator)” on a 2012 (ODI 11716476). Toyota’s T-SB-0024-19 covers 2011–2015 Prius and 2012–2015 Prius Plug-in Hybrid cars “where the brake, ABS, and/or TRAC warning light(s) are on and/or a Check VSC message displays”. That 2012 owner also mentions extended Toyota coverage for the booster pump; ask a dealer about it by VIN.
Purge line. T-SB-0041-15 (June 30, 2015) covers 2010–2013 Prius and 2012–2013 Prius v with P0A0F (Engine Failed to Start), caused by the purge VSV/PCV line’s “separation from the throttle body housing”. It also lists P3190, P3191 and P0171.
2012 Prius v. A Toyota letter for certain 2012 Prius V and certain 2011–2012 Highlander HV says the exhaust gas “control actuator may develop a coolant leak”, which lights the water temperature indicator and the check engine lamp. The free replacement was “offered until May 31, 2015”. The liftback was not part of it.
2016–2022: fourth generation
Nine of 357 complaints mention the light; four trace coolant loss to the exhaust heat exchanger, several citing the bulletin themselves (ODI 11667430, a 2019; ODI 11738755, a 2017). Toyota’s T-SB-0135-19 (September 26, 2019) covers 2016–2019 Prius and 2017–2019 Prius Prime with low coolant, “MIL ON accompanied by DTC P148F00” or poor heater performance, “due to a coolant leakage at the front exhaust pipe heat exchanger”. The repair is an updated front exhaust pipe.
Recall 17V-658 replaces the inverter on certain 2016 Prius whose capacitor “may not have been properly bolted”, which can shut the hybrid system down. Recall 21V-734 updates software on certain 2022 Prius and Prius Prime whose ECU may falsely detect an error and “shut down the hybrid system, causing a loss of drive power”.
Other bulletins that name the light: T-SB-0014-18 (2016, P1CB7A2), T-SB-0016-24 Rev1 (2016–2022, P210015) and T-SB-0319-17 (2016–2017, P05A072 with a grille shutter message).
2023 and newer
Only 1 of 63 complaints mentions the light, too few to say anything about. Campaign 24TC08 is for the 2023 Prius Prime (fuel filler clamp, vapor leak detection), not the regular Prius.
Reading and clearing the code
Write down the code and the screen message before anyone clears it. Toyota’s 23TE03 letter says a dealer finds the inverter codes with Techstream; for your own tool, see our scanner picks. After the repair, the reset guide covers clearing the light, and the check engine light overview covers Toyotas in general.
How we counted
Complaints come from NHTSA’s public API (complaintsByVehicle), pulled October 16 and 17, 2026. A complaint mentions the light if its narrative says check engine, engine light, CEL, malfunction indicator or MIL light; that also catches owners who write that the light did not come on, so the narratives were read. Every name NHTSA files the Prius under was pulled, duplicates removed by ODI number, and model and year taken from each complaint’s own vehicle record. About 70 records listing only the make were dropped. Toyota’s documents are quoted from the copies filed with NHTSA, or from NHTSA’s summary where that is all there is.