Q: Codes P1337, P0325 & P0420

The three trouble codes do not constitute a diagnosis, at all. All the three codes do is point to vehicle systems, each of which in turn contain many individual parts, wiring and so forth, any of which could be the root cause behind the trouble code. P1337 refers to the Crankshaft Position Sensor circuit but that code could have arisen if merely the wiring to the sensor is bad, if the sensor is bad or for other reasons. It is only after the code is pulled, that an actual diagnostic is performed and only after that diagnostic is performed can the cost be determined. If the problem is just a loose wire and the sensor is fine, the cost is minimal. If the problem is the sensor output is faulty and thus the sensor itself has to be replaced, then the cost to repair is the cost of the sensor plus the labor cost to get to the sensor. The other code relates to the knock sensor. Again, there is both the sensor and the wiring. The sensor could be good but the wiring is faulty, or vice versa. No one will know which it is until an actual diagnostic is performed. The final code P0420 has many, many potential causes including a damaged muffler or leaks in the muffler, damaged exhaust manifold or leaks in the exhaust manifold, damaged exhaust pipe or exhaust pipe leaks, misfiring in the engine, oil contamination in the catalytic converter, a faulty catalytic converter, a faulty engine coolant temperature sensor, faulty front oxygen sensor, faulty rear oxygen sensor, damaged oxygen sensor wiring, oxygen sensor wiring that is not properly connected, damaged oxygen sensor connectors, a fuel injector that is leaking, fuel pressure that is high, and other causes. The only way to determine which of these faults is the cause is through a diagnostic. If you desire that all three of these codes be properly and professionally diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a check engine light diagnostic and the responding certified mechanic will get this promptly resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you and we want you to understand, as thoroughly as possible, what exactly is involved in auto diagnostics and repairs.