P0408Emissions
EGR Sensor B Circuit High
P0408 means the PCM detected the EGR position sensor B circuit is reading high voltage, often an open circuit, a short to power, or a failed sensor.
🚗 Yes, but the EGR system may operate incorrectly, affecting emissions and drivability.
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🎯 Top Causes, Ranked by Likelihood
#1Faulty EGR position sensor B$80-$250
A failed sensor outputs high voltage.
#2Open or high-resistance wiring$100-$250
An open signal or ground wire raises the reading.
#3Short to power in wiring$100-$250
A wire touching voltage pulls the circuit high.
#4Poor connector contact$20-$100
A corroded connector produces a high reading.
🩺 Common Symptoms
- Check engine light
- Rough idle
- Hesitation
- Failed emissions test
- Reduced performance
💰 Repair Cost: DIY vs Shop
📋 Free OBD2 Code Cheat Sheet
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🔧 How to Diagnose P0408
1Inspect the EGR sensor B connector and wiring
2Check the ground circuit for an open
3Measure the sensor signal voltage
4Replace the EGR position sensor if faulty
❓ Frequently Asked Questions
Can I drive with P0408?
Yes, but EGR operation may be off, affecting emissions. Repair it soon.
What does P0408 mean?
The EGR position sensor B circuit reads high voltage, usually an open circuit, a short to power, or a bad sensor.
How much to fix P0408?
A replacement position sensor is $80-$250, and wiring repairs run $100-$250.
🔗 Related Codes
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