SureTrack Real Fix: Just The Right Dose

Real Fixes from ShopKey’s SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read on to see how SureTrack can help you correct issues that are not easily diagnosed using OEM information alone. SureTrack is currently available free with the purchase of a current Snap-on® diagnostic software version or in our ShopKey Pro product.


Diesel engines have inherently dirty emissions and need help to address this problem. You can run them extra lean to keep the soot down but that causes high nitrogen oxides (N0x). A common solution is to use a Diesel Exhaust Fluid (DEF) which is injected into the exhaust system to reduce the NOx emissions. Follow this Real Fix to see how a problem with the DEF system on this 2011 RAM truck was diagnosed and corrected.

Vehicle
2011 RAM Cab & Chassis 3500 HD 6.7L

Title
P20EE, Replaced Diesel Exhaust Fluid Dosing Valve

Complaint
The customer states the check engine light is on.

Cause
Connected a scan tool and found code P20EE – SCR NOx Catalyst Efficiency Below Threshold (Bank 1). Performed a visual inspection of the exhaust system and found no obvious faults. Performed a visual inspection of the diesel exhaust fluid and found that there were no leaks, the fluid was clean and at the proper level. Removed the diesel exhaust fluid dosing valve to inspect and found no obtructions in the decomposition tube. Placed the diesel exhaust fluid dosing valve in a container to capture diesel exhaust fluid expelled during flow volume testing. Used scan tool to perform diesel exhaust fluid doser pump override test. Waited test time duration and found the measured fluid collected was below specification. These test results verified the diesel exhaust fluid dosing valve was faulty.

Correction
Replaced the diesel exhaust fluid dosing valve, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.


SureTrack® adds to the power of ShopKey Pro with an exclusive combination of expert knowledge and detailed parts replacement records, all wrapped in an interactive community. Designed to help automotive shops increase accuracy and efficiency from diagnosis to completed repair, the industry’s most comprehensive repair information resource is just a few clicks away.

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About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.