4WD Range Signal Circuit High
The P27A0 code indicates that the Powertrain Control Module (PCM) has detected a voltage signal from the Four Wheel Drive (4WD) range sensor that is higher than the expected range. This sensor monitors the position of the transfer case (e.g., 2WD, 4HI, 4LO). A high voltage reading typically points to a short to power, a faulty sensor, or a wiring issue. This can prevent the 4WD system from engaging or disengaging properly.
01. Most Common Causes
- Faulty 4WD range sensor
- Short to voltage in the sensor circuit
- Damaged wiring or connector
- Corroded terminals
- Faulty PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- 4WD system inoperative or stuck in one mode
- Inability to shift between 2WD and 4WD
- Erratic 4WD engagement
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all codes and freeze frame data.
Step 2: Inspect the 4WD range sensor and its wiring for damage, corrosion, or loose connections.
Step 3: Measure voltage at the sensor signal wire; compare to manufacturer specifications.
Step 4: Test the sensor resistance and continuity per service manual.
Step 5: If wiring and sensor are okay, check for PCM issues or perform a relearn procedure.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as the 4WD system may not function correctly, potentially causing unsafe driving conditions, especially off-road or in slippery conditions.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, including parts (sensor $50-$150) and labor ($100-$250), depending on the vehicle and shop rates.