Gear Shift Position Circuit Intermittent
The P0918 code indicates an intermittent fault in the gear shift position circuit, which monitors the position of the gear selector (PRNDL). This circuit uses sensors or switches to inform the transmission control module (TCM) or powertrain control module (PCM) of the selected gear. An intermittent signal can cause erratic shifting, failure to start, or incorrect gear engagement. Common causes include a faulty range sensor, damaged wiring, or a loose connector.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Vehicle may not start or shift out of Park
- Erratic or harsh shifting
- Transmission stuck in limp mode or a single gear
2. Most Common Causes
- Damaged, corroded, loose, or intermittently shorted wiring or connectors in the shift position sensor circuit
- Faulty transmission range sensor (TRS) / neutral safety switch with worn internal contacts
- Loose or misaligned sensor mounting relative to the shift lever
- Intermittent internal failure of the TCM/PCM (rare)
- CAN bus communication issues if the signal is transmitted digitally
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data to confirm P0918.
Step 2: Visually inspect the transmission range sensor and wiring harness for damage, corrosion, or loose connections.
Step 3: Test the range sensor resistance and voltage according to manufacturer specifications.
Step 4: Check for intermittent faults by wiggling the wiring harness while monitoring the sensor signal with a multimeter or scan tool.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. The intermittent circuit can cause sudden loss of gear selection, leading to unsafe driving conditions or transmission damage.
How much does it cost to fix?▼
Repair costs typically range from $50 to $150 for diagnostic and minor repairs like cleaning connectors or replacing a sensor, but could be higher if wiring replacement is needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.