P0402 on Subaru
Exhaust Gas Recirculation Flow Excessive
P0402 on Subaru vehicles indicates exhaust gas recirculation flow excessive. Au7o has documented this code across 2 Subaru models — most commonly on Baja, Tribeca. 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 Subaru range from $200 to $3,000, 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 Subaru by Model
Subaru Baja(2 issues)
- Bed and Rear Quarter Panel Rust2003-2006
The Baja's composite bed and steel rear quarter panels are prone to significant rust, particularly in salt-belt states. The junction between the composite bed panels and steel body structure traps moisture and road salt, accelerating corrosion. The rear wheel arches, bed floor seams, and tailgate hinges are common failure points. Severe rust can compromise structural integrity of the bed mounting points. Due to the Baja's rarity (only ~30,000 produced), replacement panels are extremely scarce and expensive.
- Rear Strut Tower Rust and Structural Weakening2003-2006
The Baja's rear strut towers (located under the bed) are highly susceptible to rust, which can compromise the structural integrity of the suspension mounting point. Water and debris accumulate around the strut towers due to the bed design, and inadequate factory rustproofing allows corrosion to progress rapidly. A severely rusted strut tower can crack or separate, causing sudden loss of rear suspension control. This is a known safety concern for Bajas in the rust belt.
Subaru Tribeca(1 issue)
- 5-Speed Automatic Transmission Torque Converter Shudder2010-2014
The 2010-2014 Tribeca uses a 5-speed conventional automatic transmission (5EAT) rather than a CVT, but it still suffers from torque converter shudder and lockup clutch issues. The torque converter lockup clutch develops shudder during light throttle cruising at 35-50 mph, creating a vibration felt through the vehicle. The issue is caused by degraded transmission fluid or worn lockup clutch material. If the ATF is not changed regularly, the shudder progressively worsens and can lead to torque converter failure.
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View P0402 across all makes →Frequently Asked Questions
What does P0402 mean on Subaru?▼
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 Subaru specifically, this code is documented across 2 models.
What causes P0402 on Subaru vehicles?▼
Common causes on Subaru: 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 Subaru?▼
Repair costs on Subaru range from $200 to $3,000, depending on the specific model and root cause.
Which Subaru models have P0402 documented?▼
Au7o has documented P0402 on 2 Subaru models: Baja, Tribeca.