Shift Solenoid 'B' Control Circuit Low
The P0998 code indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the control circuit of shift solenoid 'B'. This solenoid is responsible for directing transmission fluid to engage specific gears. A low circuit condition can be caused by a faulty solenoid, damaged wiring, poor electrical connections, or a malfunctioning PCM. This issue can lead to improper transmission operation, harsh shifting, or failure to shift.
01. Most Common Causes
- Faulty shift solenoid 'B'
- Damaged or corroded wiring/connectors in the solenoid circuit
- Low transmission fluid level or dirty fluid
- Faulty PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission stuck in gear or fails to shift
- Harsh or erratic shifting
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition.
Step 3: Visually check wiring and connectors for damage or corrosion.
Step 4: Test solenoid resistance and power/ground circuits with a multimeter.
Step 5: If necessary, perform a solenoid actuation test using a scan tool.
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 it can cause transmission damage or unsafe driving conditions. Have the vehicle inspected immediately.
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.