P0402 on Kia
Exhaust Gas Recirculation Flow Excessive
P0402 on Kia vehicles indicates exhaust gas recirculation flow excessive. Au7o has documented this code across 4 Kia models — most commonly on EV6, Forte, Niro. 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 Kia range from $50 to $9,200, 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 Kia by Model
Kia EV6(1 issue)
- ICCU Failure and 12V Battery Drain2022-2024
The Integrated Charging Control Unit (ICCU) in the 2022-2024 EV6 can malfunction and stop charging the 12V battery from the main high-voltage battery pack. This causes the 12V battery to drain, resulting in a no-start condition and loss of drive power. NHTSA recall covers affected vehicles. The ICCU is responsible for converting high-voltage DC to 12V DC and managing Vehicle-to-Load (V2L) functionality. Lemon law firms report receiving nearly 200 calls per month for EV6 ICCU issues.
Kia Forte(1 issue)
- Headlight and Taillight Moisture Condensation2019-2023
The 2019-2023 Forte commonly develops condensation (fogging) inside the headlight and taillight assemblies. Water enters through degraded seals or vent tubes that become clogged. In severe cases, standing water can short out LED driver boards or corrode wiring connectors. Kia has replaced headlight assemblies under warranty for many owners, though the issue can return if the seal design is not updated.
Kia Niro(2 issues)
- Regenerative Braking Loss and Reduced Braking Power2017-2019
The 2017-2019 Niro Hybrid can experience sudden loss of regenerative braking followed by reduced overall braking power. The integrated brake system that blends regenerative and friction braking can malfunction, leaving only friction brakes active with increased pedal effort. The brake system electronic control module may need reprogramming or replacement. This is a safety concern as stopping distances increase significantly.
- Onboard Charger (OBC) Failure (Niro EV)2019-2023
The Niro EV onboard charger (OBC) module can fail, preventing the vehicle from AC charging (Level 1 and Level 2). The OBC converts AC power from the charging station to DC for the battery. Failures are often caused by thermal stress or component degradation. DC fast charging may still work as it bypasses the OBC. Replacement of the OBC is expensive and requires dealer service.
Kia Optima(1 issue)
- Hybrid High-Voltage Battery Degradation2011-2020
Hybrid Optima vehicles may experience high-voltage battery cell failure or degradation, typically after 6-10 years of use. When the battery fails, fuel economy drops significantly, warning lights appear, and hybrid system functionality is compromised. Dealership replacement costs are extremely high, though aftermarket options exist.
Looking for P0402 on a different make?
View P0402 across all makes →Frequently Asked Questions
What does P0402 mean on Kia?▼
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 Kia specifically, this code is documented across 4 models.
What causes P0402 on Kia vehicles?▼
Common causes on Kia: 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 Kia?▼
Repair costs on Kia range from $50 to $9,200, depending on the specific model and root cause.
Which Kia models have P0402 documented?▼
Au7o has documented P0402 on 4 Kia models: EV6, Forte, Niro, Optima.