What’s wrong with the VW Passat that accelerates poorly while driving, shakes at total speed, and stalls easily? This case is explained below!
A mileage of 170,000km 2008 Volkswagen Passat B5 1.8T sedan. Acceleration is not smooth during driving, total speed shaking, and even stalled 2 times on the road, has been repaired 2 times, but the fault has not been eliminated.
Diagnostic analysis: First of all, to verify the fault, the idle speed is good and bad, the road test and acceleration performance are not good, and waiting for the red light when the vehicle is shaking is obvious.
Connected to the diagnostic instrument check, the fault code is displayed as “intake camshaft control circuit disconnection, occasional”. Fault code can be cleared, but will soon reappear, and there is no sign. Execution of component testing, you can hear the camshaft adjustment valve N205 issued by the “click” sound of action, but due to the occasional nature of the fault, can not be completely concluded that it is not a problem.
Looking at the wiring diagram, N205 has 2 wires, one supply wire connects to a 15A fuse numbered S301, and the other connects to pin 115 of the engine control unit (J220) T121 plug for its hitch control. Measuring the 2 wires, there is no break or short circuit. Observe the circuit diagram again, The N205 power supply line is through the main relay J271 pin 87 output, so could it be that J271 has a problem?
So I pulled out the relay and pried it open to inspect it, and saw that pin 30 of J271 had obvious signs of ablation.
Fault resolution: Replace the main relay J271, The test car fault was eliminated 1 month after the phone call back, the fault did not reoccur.
Case summaries: This fault is due to the main relay J271 pin 30 erosion, resulting in poor contact during operation. Carefully observe the circuit diagram, J271 pin 87 also through the S229 fuse to the four ignition coil power supply, then the driving stalled fault phenomenon can be understood. I picked up the car-only camshaft control circuit disconnection fault code, after consulting the user learned that the car stalled and could not be started after the fault, in other repair shops, the ignition control fault code was also found.
This fault is more common in the longer mileage of the Passat B5 models, I hope that colleagues who encounter such faults in the future can be quickly eliminated to avoid detours.
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