P0402 OBD-II Trouble Code: Exhaust Gas Recirculation Flow Excessive Detected

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0402 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0402 code

P0402 is a diagnostic trouble code (DTC) for "Exhaust Gas Recirculation Flow Excessive Detected". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $69.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$69.99$20.00
Toyota$69.99$20.00
BMW$69.99$20.00
SCHEDULE P0402 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P0402 code definition

Exhaust Gas Recirculation Flow Excessive Detected

What the P0402 code means

P0402 is an OBD-II generic code that the engine control module (ECM) has detected indicating the engine exhaust gas recirculation (EGR) valve is flowing too much recirculated exhaust gases when it is commanded to open the flow of gases into the intake manifold.

What causes the P0402 code?

  • The EGR valve is opening all the way or more than needed due to a blocked vacuum diaphragm in the EGR vacuum back pressure valve.

  • The EGR temperature sensor is registering too much of a temperature change when the EGR valve is opened from a partly blocked exhaust catalyst causing excessive back pressure in the EGR system.

  • The EGR is stuck open due to binding or carbon deposits holding the valve open.

What are the symptoms of the P0402 code?

  • The Check Engine Light will be illuminated and the code is set in ECM memory.
  • The engine could be running rough if the valve is stuck open.
  • The engine EGR system may have exhaust leaks at the back pressure transducer.

How does a mechanic diagnose the P0402 code?

  • Scans codes and documents the freeze frame data in order to verify the problem.

  • Clears the engine and ETC codes and road tests to verify that the code comes back.

  • Visually checks the vacuum hoses, wiring, connections to the EGR valve, and control solenoid, along with the EGR temperature sensor and back pressure transducer.

  • Disconnects and checks to see if the EGR valve vacuum can be controlled to the valve when the control solenoid opens on light-to-medium acceleration and not just when it is open fully.

  • Checks the exhaust catalyst for damage or excessive back pressure on the EGR system.

  • Removes EGR valve and temperature sensor to check for carbon holding the EGR valve open or the EGR bleed port not being blocked with carbon not allowing the valve to bleed off vacuum.

Common mistakes when diagnosing the P0402 code

  • Replacing the EGR valve without checking the EGR pressure transducer to see if it can control the EGR valve opening.

  • Not checking to see if the EGR valve is being held open mechanically by a piece of carbon before replacing it.

How serious is the P0402 code?

  • An EGR that has excessive flow can cause the engine to hesitate or stall on acceleration or have a very rough engine idle.

  • The Check Engine Light on will cause the vehicle to fail emission testing.

  • If the catalyst is blocked causing code, then it could cause engine to lose power or not start.

What repairs can fix the P0402 code?

  • Replacing the stuck open EGR valve

  • Replacing a broken catalyst in the exhaust

  • Replacing an EGR temperature sensor or cleaning the carbon off of it to repair it if it registers too much of a temperature change

  • Replacing the EGR backpressure control valve

Additional comments for consideration regarding the P0402 code

Code P0402 is triggered when the EGR temperature sensor sees more of a temperature change than the EGR has commanded to open. This is usually caused by the EGR backpressure control valve getting a burnt diaphragm from the exhaust backpressure over time or from a partly blocked catalyst.

Need help with a P0402 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

trouble codes
P0402
Check Engine Light

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0402 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

4,240

Rating Summary
3,884
174
45
26
111
3,884
174
45
26
111
Tyrone

Tyrone

6 years of experience
107 reviews
Tyrone
6 years of experience
He showed up on time and got my diagnostic done quickly. He also gave me honest recommendations on what I need to do for my car.
2008 HONDA ACCORD - CHECK ENGINE LIGHT IS ON - CULVER CITY, CALIFORNIA
Michael

Michael

13 years of experience
379 reviews
Michael
13 years of experience
Very knowable. Identified proble that was different from whatI had identified.Also will save me cash.
2003 FORD MUSTANG - CHECK ENGINE LIGHT IS ON - SMYRNA, GEORGIA
Mario

Mario

18 years of experience
48 reviews
Mario
18 years of experience
Very professional with his work, he was able to locate the problem within minutes. Awesome work!
2004 HYUNDAI SONATA - CHECK ENGINE LIGHT IS ON - NAPLES, FLORIDA
Stefan

Stefan

14 years of experience
366 reviews
Stefan
14 years of experience
Saved me 3 hours on some Saturday!! 3 hours I would never get back! thanks! Greg
1994 FORD TAURUS - CHECK ENGINE LIGHT IS ON - DUBLIN, CALIFORNIA

More related articles

P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222...
How to Get a Louisiana Driver's Permit
s licensing program. The first step in this program is to obtain...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...

Related questions

Q: engine wont restart when hot, no spark P0340 has 12v on both connectors, freq from 5-11hz when cranking

Since the crank position sensor gets its timing signal off the damper, I would first replace the damper to be sure timing was correct. The fact that this failure occurs after a "heat soak" cycle, and the P0340 code is...

Q: Shaking when in overdrive

Hi there. Check the fuel system and see if the fuel injector for cylinder number 2 is malfunctioning. The code P0402 means that the EGR is not functioning and the code P0174 means that Bank 2 is lean, which is...

Q: check emission system and burning smell 2010 Acura TSX

Hello - you have multiple, unrelated problems here. The Vehicle Stability Assist (VSA) system may only have a problem with a wheel speed sensor, a common problem with electronic stability and anti-skid brake systems. The emissions and "burning smell" problem...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com