Exhaust Pressure Sensor Communication Bus Off
The U0549 code means the vehicle's onboard diagnostic system has detected: Exhaust Pressure Sensor Communication Bus Off. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $150 - $500
Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.
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Common Symptoms
- Check engine light on
- Reduced engine power in diesel vehicles
- DPF regeneration issues
- Increased exhaust smoke
Probable Causes (Ranked by Likelihood)
- Exhaust pressure sensor failure Very High
- Sensor tube clogged with soot High
- Wiring damage from exhaust heat Moderate
- ECM communication fault Low
Step-by-Step Diagnostic Procedure
-
Inspect exhaust pressure sensor tubes for soot buildup
-
Test sensor output values at idle and under load
-
Check wiring for heat damage near exhaust
-
Clear codes and verify DPF regeneration completes
Frequently Asked Questions
Can I drive with U0549?
Check the severity. If it affects safety systems like stability control or braking, limit driving to short distances. Comfort features like heaters or parking assist are safe to drive with.
What causes U0549?
Most commonly a faulty exhaust pressure sensor or damaged wiring in the communication circuit to that module.
How much does it cost to fix U0549?
Typical repair costs range from $150 - $500 depending on whether the module or just wiring needs repair.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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