BMW E38 won't start or starter won't crank
Why does the E38 starter not crank when the key is turned?
When you hear only a click, the cause is often a weak battery, a poor terminal or ground, a faulty starter motor or loose starter bolts. A chattering starter and flickering lights point to a poor contact. First measure the battery voltage and check the ground cable between the body and the engine.
What if the starter gets no power even though the battery is good?
The ignition switch base may be broken, in which case the starter gets no trigger signal. The starter relays and relay sockets may also be damaged if the drain hole of the relay box is blocked and the box has got wet. The fault is repaired by replacing the faulty part.
The engine cranks but does not start, what could be the cause?
Common causes are the crankshaft position sensor, which can be broken without a fault code (in live data the engine speed is zero), a failed fuel pump or too little fuel in the tank. The power supply of the engine management or the control unit itself can also be the cause.
What if there is an immobiliser or alarm fault?
Have a workshop investigate it with a diagnostic tool. Clearing fault codes or an electrical fault in the instrument cluster and control units can prevent starting, and it is not worth trying to fix it yourself.