Toyota Prius NHW20 common problems: what to check before you buy
Credov's researched list of the 3 faults the Toyota Prius NHW20 is known for (2005–2011), 3 of them serious or costly. Each one says what to look for when you check the car, so you can spot it before you buy. Not every car has these faults: they are the ones worth checking on this model.
Known problems on the Toyota Prius NHW20
Brake actuator / booster leaks inside
Safety risk
2005–2011 · hybrid · Brakes
What to look for: Turn to Ready with the engine bay quiet and listen near the brake fluid reservoir.
Why it matters: The car lights up ABS, BRAKE and VSC/TRAC together and stores C1252, C1253, C1256 or C1391. Braking becomes jerky at low speed, the pedal goes hard or long and regenerative braking blending is lost. Mostly a high-km failure; the full assembly must be replaced and bled with a scan tool. Used units are the common budget repair in NZ. Left unrepaired this is a safety risk on top of the repair bill.
What to look for: Red triangle or check-engine light on the dash.
Why it matters: The car sets P0A80 ('replace hybrid battery pack'), shows the red triangle 'Check Hybrid System' warning and the engine runs far more than normal. Corroded bus-bars between modules are common on these older packs and can trigger the same codes. Fix is a replacement or reconditioned pack; a cheap module swap often fails again within months. Left unrepaired this grows into a major repair bill.
What to look for: Take the cap off the inverter coolant reservoir (the smaller tank at the front) and look for coolant swirling/turbulence; still coolant means.
Why it matters: When it stops, the inverter overheats, P0A93 (inverter cooling system performance) sets, the car drops into reduced power and the inverter itself can be damaged. Low or old coolant and trapped air give the same code. Updated pump has a silver base (original black). Specialists have seen pump failures on cars with as little as about 90,000 km. Left unrepaired this grows into a major repair bill.
Got a question about a Toyota Prius NHW20? Ask Credov: a noise, a warning light, a part or how to fix it.
Also check on every car
On top of the faults above, every Credov inspection covers the basics: fuel smell, leaks or filler rust, engine oil leaks, power steering fluid leak, drive belt cracks or squeal, rust underneath: chassis and mounts, engine mounts, engine oil level and colour, coolant level, colour and leaks, head gasket failure signs, cold start: rattle, knock or smoke, rough or hunting idle, engine running hot on gauge, gearbox or diff oil leak, swapped gearbox without lvv and more.
Researched by Credov from manufacturer recalls and service bulletins, owner reports and workshop sources. Repair prices are typical ranges, not quotes. See also fault codes and repair costs.