What Does P208F Mean?
The DEF injector for Bank 2 Unit 1 is mechanically stuck in the closed position. The PCM detects no or insufficient DEF flow despite commanding the injector to open on the second bank.
Common Causes
40%
DEF crystallization blocking injector nozzle or valve seat
25%
Contaminated or old DEF causing deposits inside injector
20%
Failed injector solenoid or mechanical valve mechanism
10%
Frozen DEF in extremely cold temperatures
5%
Foreign debris in DEF tank contaminating injector
Diagnostic Steps
1
Step 1: Check DEF quality and age; verify proper API certification on container
2
Step 2: Monitor injector commanded vs actual flow rate with advanced scan tool
3
Step 3: Perform injector leak-down test per manufacturer specifications
4
Step 4: Check DEF supply pressure at injector rail during injection cycle
5
Step 5: Remove injector and inspect nozzle for crystallization or blockage; flush with deionized water if possible
Estimated Repair Cost
$400 - $1,800
Parts + labor, varies by vehicle and location
The DEF injector for Bank 2 Unit 1 is mechanically stuck in the closed position. The PCM detects no or insufficient DEF flow despite commanding the injector to open on the second bank.
The most common cause of P208F (Reductant Injection Valve Stuck Closed Bank 2 Unit 1) is: DEF crystallization blocking injector nozzle or valve seat
Typical repair costs for P208F range from $400 to $1,800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle will derate power progressively over multiple drive cycles. Not immediately dangerous but may leave driver stranded in reduced power mode.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P208F to identify the root cause.
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Quick Info
Category
Powertrain
System
Selective Catalytic Reduction (SCR) Emissions System
Difficulty
Type
Generic (SAE)
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