The P20F5: Reductant Consumption Too High fault code indicates that the vehicle’s reductant (Diesel Exhaust Fluid, DEF) consumption is higher than expected. This excessive consumption could point to issues with the reductant injector or calibration problems in the reductant system, potentially leading to inefficient NOx reduction and unnecessary fluid use.
P20F5 – Quick Overview
Code | Information |
---|---|
Meaning | P20F5: Reductant Consumption Too High |
Is it serious? | Yes, high reductant consumption can indicate inefficiency in the emissions system and lead to higher operational costs. |
Possible causes | – Reductant consumption higher than expected – Faulty reductant injector – Issues with reductant system calibration |
How to diagnose? | – Measure reductant consumption – Test the reductant injector – Check and calibrate the reductant system |
P20F5 Meaning
The P20F5 fault code signifies that the vehicle is consuming more reductant (DEF) than required, potentially indicating a problem in the SCR (Selective Catalytic Reduction) system. Over-consumption of DEF can result from a faulty reductant injector that is over-injecting fluid or from miscalibration within the reductant system. If left unresolved, this can lead to higher operational costs and inefficient NOx reduction.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for any additional related codes that could provide further insights into the over-consumption issue. | OBD-II Scanner |
Measure Reductant Consumption | Compare the actual reductant (DEF) consumption with manufacturer specifications using diagnostic software to verify if it exceeds expected levels. | Diagnostic Tool |
Test the Reductant Injector | Use a diagnostic tool to test the performance of the reductant injector and confirm that it is not injecting more fluid than required. | Multimeter, Diagnostic Tool |
Inspect the Reductant System | Visually inspect the reductant system for any leaks, blockages, or malfunctions that could contribute to excess reductant consumption. | Flashlight, Diagnostic Tool |
Check and Calibrate the Reductant System | Ensure the reductant system is properly calibrated to inject the correct amount of DEF based on engine load and emissions output. Perform recalibration if needed. | Calibration Tool |
Repair or Replace Faulty Components | If the reductant injector or any other parts of the system are found to be faulty, repair or replace them to restore proper function. | Replacement Parts, Tools |
Clear the Code and Test Drive | After completing repairs, clear the code using an OBD-II scanner and test drive the vehicle to confirm that the issue has been resolved. | OBD-II Scanner, Vehicle Manual |
Recheck for Codes | After the test drive, rescan the vehicle to ensure the P20F5 code does not return. | OBD-II Scanner |

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Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)