b'BMW F15 DIESEL FUEL SYSTEM SELECTIVE CATALYST REDUCTION (SCR) PUMP FUNCTION TESTINGby iScanBMW diesel models are equipped with a dual-tank selective catalyst reductionValues lower than 31.8 % will cause an improper AdBlue mixture function and (SCR) system. The SCR system is designed to reduce harmful emissions frompossible freezing.diesel engines. The system works by injecting a urea-based solution calledValues higher than 33.3% indicate too low water mixture in the AdBlue. This can AdBlue (diesel emission \x1fuid (DEF)) into the exhaust system, which then reactsoccur from a leaking SCR Tank causing water evaporation. with the exhaust gases to convert harmful nitrogen oxides (NOx) into harmless nitrogen and water vapor.Metering valve: Look for Adblue deposits around the nozzle. No Adblue is injected before the SCR catalyst through a metering valve. NOx reduc- deposits should be present at the tion is monitor using Pre- and Post-catalyst NOx sensors and using the feedbacknozzles. Deposits at sides of nozzle from the sensors the DME calculates the volume of Adblue injection. The ratio ofhave no e\x1eect on function unless the NOX to NO is monitored to determine reduction e\x1eectiveness. When Adbluedeposits overlap the nozzles. The injection occurs, line pressure can reach 6 Bar. When the engine is turned OFF,deposits have a consistency like the lines are partially drained to prevent damage from freezing.toothpaste and can be easily cleaned, Recheck spray pattern after cleaning.In this article we will focus on the 4th generation dual-tank system found in F15 X5 models with a 3.0l engine and common problems you may see in your shop. Check injection pattern using a paper First, lets review a few tests for the metering valve and the AdBlue. Then welltowel. At a distance of 7.88.7 (20 - see how to test the common issue of a faulty SCR transfer pump. 40cm) before the uncovered meter-ing module, look for three evenlyAdBlue Mixer: Checkdistributed circles (A). At a distance of that the mounting tabs6 (15cm), the metering valve injec-on the mixer are facingtion pattern should form a circle (B). the rear of the vehicle. If the tabs are facing Before digging too deep into any issue, be sure to check for technical service toward the front of thebulletins (TSBs) or software updates. If you have any of the following fault vehicle, the dosedcodes, check that the vehicle you are working on has the latest DME soft-AdBlue will not beware and the AdBlue quality is OK.distributed properly. 6F500 - SCR system, e\x1dciency: E\x1dciency too low AdBlue Quality: Check the quality of the 26F600 - SCR system, e\x1dciency: E\x1dciency too lowAdBlue using a refractometer. 2C4E00 - SCR system: System error and poor urea/water mixture quality Evaluating the AdBluedetectedmixture: Normal Range: 31,8% - 33.3%.26FD00 - Reducing agent metering, long-term adaptation: Adaptation value too high21 8'