What Does the P0851 Code Mean?
The P0851 code refers to a problem with the Park/Neutral Safety Switch Input Circuit being low. This code typically indicates that the vehicle’s Powertrain Control Module (PCM) is not receiving the correct signal from the park/neutral safety switch, which is crucial for determining whether the transmission is in a safe position to start the engine.
What Causes the P0851 Code?
Several factors can lead to the P0851 code being triggered:
- Neutral safety switch failure
- Powertrain Control Module (PCM) failure
- Wiring issues or poor connections in the circuit
What Are the Symptoms of the P0851 Code?
The most common symptom associated with the P0851 code is:
- The engine may not start, as the PCM prevents starting if it cannot confirm the transmission is in Park/Neutral.
How Serious Is the P0851 Code?
The P0851 code is considered urgent. If this code is present, immediate action is recommended as it can prevent the vehicle from starting, potentially leaving you stranded. Delaying repair can lead to more significant issues that may affect vehicle safety and reliability.
How to Diagnose the P0851 Code
To diagnose the P0851 code, follow these steps:
- Use an OBD-II scanner to confirm the P0851 code.
- Inspect the park/neutral safety switch and wiring for any visible damage or corrosion.
- Test the park/neutral safety switch for proper operation using a multimeter.
- Check the PCM for any faults or updates that may be necessary.
Common Repairs for the P0851 Code
Repairs typically include:
- Replacing the neutral safety switch if it is found to be faulty.
- Repairing or replacing damaged wiring or connectors in the circuit.
- Reprogramming or replacing the Powertrain Control Module (PCM) if necessary.
How Much Does It Cost to Fix the P0851 Code?
Repair costs for the P0851 code can vary widely based on the specific issue:
- Neutral safety switch replacement: $100 to $300
- Wiring repairs: $50 to $200
- PCM replacement: $400 to $1,500
Can I Fix the P0851 Code Myself?
If you have experience with automotive repairs and diagnostics, you may be able to address the P0851 code yourself, especially if it’s a wiring issue or a simple switch replacement. However, for more complex issues such as PCM replacement or if you are uncertain, it is advisable to consult a professional mechanic.
