B0840 Engine Trouble Code
What is B0840?
The B0840 check-engine light can indicate issues ranging from minor (loose gas cap) to serious (catalytic converter failure). Professional diagnostic scanning at a dealer or shop will identify the exact cause and required repairs.
Code Information
| Code Type: | OBD-II Body (B) Trouble Code |
| System: | Body |
| Code: | B0840 |
B0840 Symptoms
Check Engine Light
Illuminated dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration
Starting Problems
Difficulty starting the engine
B0840 Code Structure
Understanding what each digit means in the B0840 body trouble code:
| B | 0 | 8 | 4 | 0 |
|---|---|---|---|---|
| Body Code | Intake Valve Control Solenoid Circuit Low | Engine Oil Temperature Sensor Malfunction | Injection Pump Fuel Metering Control 'B' High | Shift Solenoid E Performance or Stuck Off |
How to Fix B0840
Diagnostic Steps:
Check if fuel pump primes when key is turned to ON. Measure fuel pressure and verify bright white-blue spark at all plugs. Also verify mechanical timing alignment.
Repair Solution:
Disconnected, dirty, or fouled spark plugs commonly prevent proper engine operation. Replace spark plugs every season or 25 hours. Verify proper spark plug gap. If plugs are good, check ignition components: spark plug wires, coils, and ignition module.
Technical Notes:
Parts or components should not be replaced based solely on B0840 DTC. Consult your vehicle service manual for proper diagnostic procedures, possible causes, and required testing before replacement.
B0840 Description
B0840 engine trouble code is related to Shift Solenoid E Performance or Stuck Off.
Main Cause
The primary reason for B0840 OBD-II Engine Trouble Code is: Engine Oil Temperature Sensor Malfunction.