B1686 BMW Fault Code
Check B1686 OBD Fault Code ReasonLow Speed Fuel Pump Primary Circuit Malfunction The PCM monitors the low speed fuel pump (LFP) primary circuit output from the PCM.
The test fails if: When the LFP circuit is commanded on (grounded), excessive current draw is detected on the BMW LFP circuit; or when the LFP circuit is commanded off, voltage is not detected on the LFP circuit (the PCM expects to detect VPWR voltage coming through the low speed fuel pump relay coil to the LFP circuit). Open or shorted low fuel pump (LFP) circuit Open VPWR to low speed fuel pump relay Damaged low speed fuel pump relay Damaged PCM An open circuit or short to ground can only be detected with the low speed fuel pump.
B1686 Code Symptoms :
If your vehicle failed a B1686 test and the B1686 Check Engine Light is NOT on, chances are you have a problem with the OBDII system, a burned out MIL lamp, or a faulty catalytic converter. The converter is essentially an afterburner that cleans up the exhaust after it exits the engine. The OBDII system uses B1686 a ownstream oxygen sensor to monitor the efficiency of the converter, and it should detect a drop in converter efficiency if the converter has been contaminated or is failing (ignition misfiring, leaky exhaust valves, and oil burning can all damage the converter). What you want to look : Any conditions that might cause ignition misfire, an overly rich or lean fuel condition, or loss of compression.
Diagnosis And Repairing B1686
B1686 the main thing to check is to verify the operation of the VCT solenoid. You're looking for a sticking or stuck VCt solenoid valve caused by contamination. Refer to vehicle specific repair manual to perform component tests for the VCT unit.
How to fix B1686 code ?
- Camshaft Position Sensor harness is open or shorted
- Camshaft Position Sensor harness is open or shorted
- Continuous oil flow to the VCT piston chamber
- Faulty front heated oxygen sensor
Regardless of the design though, the purpose of all clutch actuating systems is to improve the driving experience by removing the need for manual clutch operation by the driver.
Computer-controlled clutch actuating systems work particularly well in dual clutch systems where one clutch controls gear changes of even-numbered gear ratios, and a second clutch that controls gear changes of odd-numbered ratios.
