What Does P1408 Mean?
During the Key On Engine Running (KOER) self-test, the EGR system flow did not meet expected parameters. This indicates the EGR valve is not flowing the correct amount of exhaust gas during the diagnostic test.
Common Causes
35%
Carbon buildup in EGR valve or passages restricting flow
30%
EGR valve mechanical failure or sticking
20%
DPFE sensor reading incorrectly or out of calibration
10%
Vacuum leaks affecting EGR system operation
5%
EGR valve control solenoid failure
Diagnostic Steps
1
Step 1: Perform visual inspection of EGR valve for carbon buildup and movement
2
Step 2: Command EGR valve open using scan tool active tests while monitoring DPFE sensor response
3
Step 3: Remove and clean EGR valve and passages, check valve pintle for free movement
4
Step 4: Test EGR vacuum solenoid operation and vacuum supply to EGR valve
5
Step 5: Verify DPFE sensor reading changes appropriately when EGR valve is commanded open/closed
Estimated Repair Cost
$150 - $500
Parts + labor, varies by vehicle and location
During the Key On Engine Running (KOER) self-test, the EGR system flow did not meet expected parameters. This indicates the EGR valve is not flowing the correct amount of exhaust gas during the diagnostic test.
The most common cause of P1408 (EGR System Flow Out of Key On Engine Running Self Test Range) is: Carbon buildup in EGR valve or passages restricting flow
Typical repair costs for P1408 range from $150 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive but will fail emissions testing and may experience poor performance. Address within two weeks to maintain proper engine operation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1408 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control System (EGR)
Difficulty
Type
Manufacturer
Recommended Tools
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