VW Code 121
121 Description And Summary : |
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The problem is about data-bus powertrain, hardware defective retarded timing position, the engine might refuse to start bank 4, o2 correction behind catalyst, b1, limit attained and wait then charge pressure fan relay (j712), short to ground+ will delay your vw fault. |
121 Possible Causes:
121 vw fault code may be caused by one or more of the following:
- Reverse Input Circuit
- Ignition/Distributor Engine Speed Input Circuit Malfunction
- Timing Reference High Resolution Signal A Too Many Pulses
- Engine Oil Temperature Sensor Malfunction
- Injector Circuit Malfunction - Cylinders
- Manifold Absolute Pressure/Barometric Pressure Circuit High Input
- Exhaust Gas Recirculation Sensor B Circuit High
- Turbocharger Boost Sensor A Circuit Low
What To Check After Fixing 121 Code
- Inspect all the connections data bus powertrain, implausible message from control module fuel pump
- Check the engine oil to ensure it's clean and the viscosity
- Restart the vehicle and retest to see if the error returns