P1841 Front Axle Speed Sensor Circuit Malfunction
The P1841 code indicates that the powertrain control module (PCM) or transfer case control module (TCM) has detected an electrical fault in the front axle speed sensor circuit of the transfer case. This sensor monitors the rotational speed of the front output shaft to manage 4WD engagement, traction control, and stability systems. The fault may be an open circuit, short to ground, or short to voltage in the sensor's signal, ground, or reference wire.
01. Most Common Causes
02. Symptoms You Will Notice
- Illuminated Check Engine Light or 4WD warning light
- Inoperative or erratic 4WD engagement, traction control, or stability control
03. Step-by-Step Diagnosis
Scan for codes and record freeze frame data
Visually inspect the sensor wiring and connectors for damage, corrosion, or looseness
Test the sensor's resistance and reference voltage per manufacturer specifications
Check for mechanical damage to the tone ring or reluctor inside the transfer case
If all else is normal, suspect a PCM/TCM fault and perform further module diagnostics
1. Frequently Asked Questions
Is it safe to drive?▼
You can drive short distances, but avoid off-road or slippery conditions as 4WD and stability systems may not function properly. Have it diagnosed soon to prevent further issues.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, including parts and labor, depending on the cause and vehicle model.