P049B

Symptoms

• Check Engine Light Is On
• Engine knocking under load (due to high combustion temperature without sufficient recirculation)
• Increased fuel consumption
• Reduced cravings
• Unstable engine operation
• Increased emissions of nitrogen oxides (NOx)
• Exhaust smell is stronger than usual

Causes

• Severely clogged EGR valve B with carbon deposits (the most common cause)
• Clogged EGR channels in the intake manifold with solid deposits
• EGR valve stuck closed
• Clogged EGR cooler (recirculated gas cooler)
• Damage to the valve drive - the valve does not open to the desired position
• Blockage in the EGR high pressure line (diesel)

How to Fix

1. Carry out activation test of EGR valve B via scanner: check if the valve opens 100%
2. Remove EGR valve B and inspect: if there is carbon deposits, clean or replace
3. Check the EGR channels in the intake manifold with a metal probe or endoscope
4. Clean the channels from carbon deposits (a specialized service can use sandblasting or dry cleaning)
5. Check the EGR cooler for permeability - if clogged, blow it out or replace it
6. After cleaning, perform the activation test again to ensure normal flow
7. Replace the valve if cleaning is impossible
8. Reset codes and monitor EGR flow on a test drive

Related codes

Error P049B by Vehicle Brand