P0402 on Toyota
Exhaust Gas Recirculation Flow Excessive
P0402 on Toyota vehicles indicates exhaust gas recirculation flow excessive. Au7o has documented this code across 9 Toyota models — most commonly on 4Runner, Avalon, Highlander. P0402 means the Exhaust Gas Recirculation (EGR) system is flowing too much exhaust back into the intake. The EGR system intentionally routes a small amount of inert exhaust gas into the engine to lower combustion temperatures and reduce nitrogen-oxide emissions, but the flow must be metered precisely. When the PCM determines the flow is excessive — often because the EGR valve is stuck open or letting gas through when it shouldn't — it sets this code. Too much EGR can cause rough idle, stalling, hesitation, and a check engine light. Typical repair costs on Toyota range from $100 to $15,000, depending on the specific model and root cause.
Common Causes of P0402
- •EGR valve stuck open or not closing fully
- •Failed or sticking EGR valve diaphragm/solenoid
- •Carbon buildup holding the EGR valve open
- •Faulty EGR position or differential pressure (DPFE) sensor
- •Leaking EGR valve gasket or pintle seat
- •Vacuum control or solenoid fault commanding EGR open
- •Wiring or connector problems in the EGR control circuit
P0402 on Toyota by Model
Toyota 4Runner(1 issue)
- Frame Rust and Corrosion2010-2019
The frame on 4Runners, especially in northern/salt belt states, can develop severe rust and corrosion. This is a safety concern as the frame provides structural integrity. Toyota had a frame replacement program for some Tacomas/Tundras but 4Runners were not included.
Toyota Avalon(1 issue)
- 6-Speed Automatic Transmission Torque Converter Shudder2013-2018
The Aisin U660E 6-speed automatic develops torque converter lockup shudder at 25-50 mph under light throttle. The lockup clutch material degrades, causing vibration during cruising. Fluid degradation accelerates the problem.
Toyota Highlander(1 issue)
- Hybrid Battery Pack Degradation and Failure2006-2013
Highlander Hybrid NiMH battery packs degrade over time, with individual cells failing after 8-12 years or 150,000+ miles. Failed cells cause reduced fuel economy, loss of hybrid assist, and eventual inability to start the vehicle.
Toyota Land Cruiser(1 issue)
- KDSS (Kinetic Dynamic Suspension System) Hydraulic Leaks2008-2021
The KDSS system uses hydraulic cylinders connected to the front and rear stabilizer bars to improve both on-road handling and off-road articulation. The hydraulic lines, cylinders, and accumulator develop leaks over time, causing KDSS warning lights and degraded handling.
Toyota Previa(1 issue)
- EGR System Carbon Buildup Causing Rough Idle and Stalling1991-1997
The Previa's mid-mounted 2TZ engine is prone to severe EGR valve and passage carbon buildup due to its unique layout and higher operating temperatures. Carbon accumulation restricts EGR flow, causing rough idle, hesitation, and stalling. The EGR passages in the intake manifold can become completely blocked by 100,000 miles.
Toyota Prius(1 issue)
- Hybrid Battery Pack (HV Battery) Failure2004-2015
Gen 2 (2004-2009) and Gen 3 (2010-2015) Prius NiMH battery packs commonly fail between 8-15 years. Individual cell degradation causes voltage imbalances, triggering warning lights and reduced performance. Battery cooling fan clogging accelerates failure.
Toyota Prius V(1 issue)
- EGR Cooler Cracking and Coolant Leak2012-2017
The Prius V shares the same 2ZR-FXE engine as the standard Prius and is subject to EGR cooler cracking. The EGR cooler develops internal cracks from thermal stress, allowing coolant to leak into the EGR passage or externally onto the engine. This causes coolant loss, overheating risk, and white smoke from the exhaust. Toyota extended warranty coverage for this issue under a Customer Support Program.
Toyota Sienna(1 issue)
- Dashboard Cracking and Melting2007-2010
2nd-gen Sienna dashboards are notorious for cracking, warping, and developing a sticky/melting surface, especially in hot climates. The dashboard material degrades from UV exposure and heat, creating a hazardous glare and releasing a sticky residue.
Toyota Tundra(1 issue)
- Cam Tower Oil Leak2007-2021
The 5.7L iForce V8 engine is known for developing oil leaks at the cam tower due to Toyota's use of gray RTV silicone sealant instead of a proper gasket from the factory. The sealant degrades over time, particularly at the rear of the cam towers where the engine is slanted.
Looking for P0402 on a different make?
View P0402 across all makes →Frequently Asked Questions
What does P0402 mean on Toyota?▼
P0402 stands for "Exhaust Gas Recirculation Flow Excessive." P0402 means the Exhaust Gas Recirculation (EGR) system is flowing too much exhaust back into the intake. The EGR system intentionally routes a small amount of inert exhaust gas into the engine to lower combustion temperatures and reduce nitrogen-oxide emissions, but the flow must be metered precisely. When the PCM determines the flow is excessive — often because the EGR valve is stuck open or letting gas through when it shouldn't — it sets this code. Too much EGR can cause rough idle, stalling, hesitation, and a check engine light. On Toyota specifically, this code is documented across 9 models.
What causes P0402 on Toyota vehicles?▼
Common causes on Toyota: EGR valve stuck open or not closing fully, Failed or sticking EGR valve diaphragm/solenoid, Carbon buildup holding the EGR valve open, Faulty EGR position or differential pressure (DPFE) sensor, Leaking EGR valve gasket or pintle seat. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0402 on a Toyota?▼
Repair costs on Toyota range from $100 to $15,000, depending on the specific model and root cause.
Which Toyota models have P0402 documented?▼
Au7o has documented P0402 on 9 Toyota models: 4Runner, Avalon, Highlander, Land Cruiser, Previa, Prius, Prius V, Sienna, Tundra.