U1558 BMW Fault Code

Description:

EGR Flow Insufficient Detected The EGR system is monitored during steady state driving conditions while the EGR is commanded on.
The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less than the desired minimum. Vacuum supply EGR valve stuck closed EGR valve leaks vacuum EGR flow path restricted EGRVR circuit shorted to PWR VREF open to D.P.F. EGR sensor D.P.F. EGR sensor downstream hose off or plugged EGRVR circuit open to PCM VPWR open to EGRVR solenoid D.P.F. EGR sensor hoses both off D.P.F. EGR sensor hoses reversed Damaged EGR orifice tube Damaged EGRVR solenoid Damaged PCM Perform KOER self-test and look for DTC U1558 as an indication of a hard fault.

U1558 Code Symptoms :

There are currently two main types of cylinder deactivation used today, depending on the type of engine. U1558 code for the pushrod design which uses solenoids to alter the oil pressure delivered to the lifters. In their collapsed state, the lifters are unable to elevate their companion pushrods under the valve rocker arms, resulting in valves that cannot be actuated and remain closed.

Diagnosis And Repairing U1558

U1558 OBD 2 code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.

How to fix U1558 code ?

• Dirty Oil
• Faulty Variable Camshaft Timing (VCT) position solenoid
• Intake Valve Timing Control Solenoid Valve harness is open or shorted
• Foreign matter caught in fuel filler cap

Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code U1558, so consult the manual to locate the brake fluid reservoir.

Bear in mind that a low fluid level can set code U1558 on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.