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EmissionsModerate✅ DIY Friendly

P0408

Exhaust Gas Recirculation Sensor B Circuit High

The secondary EGR position sensor (Sensor B) is reading a higher voltage than expected.

SeverityModerate
CategoryEmissions
Est. Repair Cost$150-$350
Code TypePowertrain
DIY RepairYes

⚡ Common Causes

⚠️ Symptoms

✅ How to Fix — Step by Step

  • Step 1:Clean EGR valve and passages
  • Step 2:Inspect wiring for shorts
  • Step 3:Test sensor voltage
  • Step 4:Replace sensor if faulty
💡 Pro Tip: Always clean the EGR valve before replacing the position sensor - carbon buildup is the more common and cheaper fix.

Repair Cost Estimate

Full Repair Estimate
$150-$350
DIY Possible?
YES
Severity
Moderate

Frequently Asked Questions

What does OBD2 code P0408 mean?+
P0408 stands for Exhaust Gas Recirculation Sensor B Circuit High. The secondary EGR position sensor (Sensor B) is reading a higher voltage than expected.
What causes code P0408?+
Faulty EGR sensor; Wiring short circuit; Carbon buildup affecting valve position
How do I fix code P0408?+
Clean EGR valve and passages; Inspect wiring for shorts; Test sensor voltage; Replace sensor if faulty
How much does it cost to fix P0408?+
Estimated repair cost for P0408 is $150-$350.
Is P0408 DIY-friendly?+
Yes — P0408 is generally DIY-friendly with basic tools.

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