Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the computer in your car is having trouble with the timing of fuel being injected into cylinder number 6 when the engine is cold. It's like trying to pour the right amount of milk into a glass at the exact right time, but your hand is a little shaky.
The engine control module (ECM) monitors the injection timing for each cylinder. If it detects that the timing for cylinder 6 is off during a cold start, it triggers this code.
The P21BB code indicates that the ECM has detected an issue with the fuel injection timing for cylinder 6 specifically during a cold start condition. This could be due to a malfunctioning injector, a timing issue, or a problem with the ECM itself.
• Rough idle during cold start
• Increased emissions
• Poor fuel economy
• Faulty fuel injector in cylinder 6
• Timing chain or belt issues
• Malfunctioning ECM
ECM: Engine Control Module
Injector: A device that introduces fuel into the engine's cylinders
• Check for any other related codes
• Inspect the fuel injector for cylinder 6
• Test the timing chain or belt for proper alignment
• Replace the faulty fuel injector
• Adjust or replace the timing chain/belt
• Reprogram or replace the ECM if necessary
• OBD-II scanner
• Fuel injector tester
• Timing light
$200 - $800
Moderate
• Ford F-150
• Chevrolet Silverado
• Dodge Ram 1500
• Regular maintenance of fuel system
• Timely replacement of timing components
• ECM software updates
Engine Performance
• Have the vehicle checked by a professional mechanic
• Avoid driving the vehicle until the issue is resolved
Check if the vehicle is under warranty for powertrain or emissions-related issues.
This code has been more common in vehicles with high mileage or those that have not been regularly maintained.
Moderate – It should be addressed soon to avoid further engine issues.
Ignoring this code can lead to increased emissions and potential engine damage.
• Engine must be cold
• Vehicle should be started from a cold state
Cylinder 6 is typically located on the engine block, and its position can vary depending on the vehicle's engine configuration.
Q: Can I drive with a P21BB code?
A: It's not recommended, as it can lead to further engine damage and increased emissions.
Q: How can I clear a P21BB code?
A: You can clear the code with an OBD-II scanner, but it's best to fix the underlying issue first.
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