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Trouble Codes & Warning Lights

Understanding check engine lights, hybrid system warnings, and what diagnostic codes actually mean.

Toyota Hybrid & EV Trouble Codes: Every Code We've Covered

When a warning light comes on, your car stores a diagnostic trouble code — a DTC. The code doesn't tell you which part to replace;...

Why Your EV Won't Wake Up: The 12V Battery Explained

Short version: When an EV won’t unlock or wake up, it’s almost always the small 12V battery, not the expensive high-voltage traction pack. The 12V...

Toyota Camry Hybrid P0A80 Code Explained

Short version: On a 2007–2011 Toyota Camry Hybrid, P0A80 means the hybrid battery has degraded and needs to be replaced. Toyota’s own scan tool spells...

Toyota Prius P148F00 Code Explained

Short version: P148F00 means Engine Coolant Pump Over Revolution — your Prius’s electric water pump is spinning faster than it should. It does that when...

Toyota Prius & Hybrid P0AA6 Code Explained

Short version: P0AA6 is a Hybrid Battery Voltage System Isolation Fault. Your hybrid runs on a high-voltage system that is supposed to be electrically isolated...

Toyota Prius P0441 & P0455 EVAP Codes Explained

Short version: P0441 and P0455 are evaporative emission (“EVAP”) system codes. P0441 means the system isn’t purging fuel vapor the way it should. P0455 means...

Prius water pump code wouldn't clear: the other shop replaced the part but missed the wire

Short version: A 2010 Prius kept setting code P261C after another shop replaced the electric water pump. The real problem was a broken signal wire...

2007 Prius P0AA6 voltage leak after reconditioned battery failed

Short version: A 2007 Prius with 200,000 miles kept setting P0AA6 — a hybrid battery voltage isolation fault — after a reconditioned battery had been...

2008 Toyota Prius P0AA6 High-Voltage Leak Diagnosis

Short version: A 2008 Prius died in a friend’s driveway with every warning light on and would not shift out of neutral. Diagnosis found two...

2016 Prius "Head Gasket" That Two Shops Couldn't Fix Was Really a Warrantied Catalytic Converter

Short version: A 2016 Prius had its head gasket replaced twice and still overheated, lost coolant, and blew white smoke. The real cause was coolant...

2009 Highlander Hybrid P0AA6: How a Leaking Sunroof Almost Cost a Hybrid Battery

Short version: A 2009 Highlander Hybrid set P0AA6 and wouldn’t start after a leaking sunroof left standing water in the back floorboards. The codes pointed...

2007 Prius U0293: Why a New Steering Sensor Killed the Hybrid System

Short version: A 2007 Prius wouldn’t start and set U0293 after another shop installed a used steering angle sensor to chase an alignment pull. The...

2014 Prius P0441 P0455 EVAP Diagnosis & Repair

Short version: This 2014 Prius came in with P0441 and P0455 still on after another shop had already replaced the fuel cap and purge solenoid....

2007 Prius Warning Lights Door Locks Water Leak Fix

Short version: A 2007 Prius came in with VSC and brake warning lights, dead door locks, and water getting into the back of the car...

2009 Prius Red Triangle After Oil Change: Rat Debris on the MAF Sensor

Short version: A 2009 Prius showed the red triangle right after an oil change and wouldn’t run — codes P3190 and P3191 pointed to fuel...

2006 Toyota Prius P0A80 P3000 Warning Lights Fixed

Short version: A donated 2006 Prius came in with warning lights and nine fault codes, including P0A80 and P3000. The codes clustered into three separate...

2007 Toyota Camry Hybrid P0A80: No Heat & Battery Fault

Short version: A 2007 Toyota Camry Hybrid came in for weak heat during electric-only driving, then added traction control and hybrid system warning lights before...

2006 Honda Civic Hybrid Dead Battery IMA Replacement

Short version: A 2006 Honda Civic Hybrid died on the freeway a week after a dealership said the failing hybrid battery could wait. The weakened...

P0A80 — Replace Hybrid Battery Pack

Short version: P0A80 is set when the hybrid battery control module determines the high-voltage pack can no longer hold or deliver a healthy charge —...

Thousands in Prius Parts Replaced. It Just Needed Gas.

A 2010 Prius owner had been fighting a “check hybrid system” message. They’d replaced the hybrid battery, the inverter, both water pumps, the MAF sensor,...

2014 Prius P0441 P0455 EVAP Diagnosis & Repair

Why It Came In The driver had already been down this road once. A previous mechanic pulled two codes, P0441 (incorrect purge flow) and P0455...

Why is my Prius getting bad MPG?

Why Your Prius’s MPG Drops in Winter — The Most Common Causes (And Why It’s Usually Normal) Cold weather is one of the most common...