Why generators show "low oil pressure shutdown": 9 documented causes and brand-specific fixes, compiled across 7 manufacturers.
Low oil level
1 brand- Generac: Verify oil level on dipstick. Add oil, if needed.
Oil pressure is less than 20 psi (138 kPa), engine has oil leaks, or oil pressure sender is faulty.
1 brand- Magnum: Check the level of the engine oil with the dipstick. Visually inspect the engine for oil leaks. If the oil level is good, restart the unit and verify the loss of oil pressure. Check the oil pressure sender.
Oil pressure is less than 20 psi, engine has oil leaks.
1 brand- Magnum: Check oil level with dipstick. Visually inspect for leaks. Restart and verify oil pressure. Check oil pressure sender.
Oil pressure is less than 20 psi (138 kPa).
1 brand- Magnum: Check oil level, inspect for leaks, and check the oil pressure sender.; Check the level of the engine oil with the dipstick. Visually inspect the engine for oil leaks. If the oil level is good, restart the unit and verify the loss of oil pressure. Check the oil pressure sender.
Low oil level, Oil leaking from engine, Oil pressure sender
1 brand- Generac: Check oil level on dipstick. Add oil if needed. Visually inspect the engine for leaks. Restart unit and verify loss of pressure. Shut down immediately if pressure does not reach 5 psi (34 kPa) within five seconds. See engine operator’s manual to identify corrective action.; Check oil level on dipstick. Add oil, if needed. Visually inspect the engine for leaks. Restart unit and verify loss of pressure. Shut down immediately if pressure does not reach 5 psi (34 kPa) within five seconds. See the OEM engine operator’s manual to identify corrective action.
Oil pressure is less than 20 psi (138 kPa), oil level is low, or oil pressure sender is damaged.
1 brand- Marathon: Check the level of the engine oil with the dipstick. Visually inspect the engine for oil leaks. If the oil level is good, restart the unit and verify the loss of oil pressure. Check the oil pressure sender on the engine block and the connecting wiring for damage.
Oil level is low or engine has oil leaks.
1 brand- Magnum: Check the oil level, visually inspect the engine for leaks, check the oil pressure sender.
This type of malfunction is caused by one of the following— 1. Low oil quantity resulting in low oil pressure. Engine oil system malfunction. Ground between TB11-30 and LOP switch. Permanently closed LOP switch. Faulty engine monitor board.
1 brand- Cummins/Onan: If the generator set has LOP pre-alarm, then the most possible reason for shutdown is either low oil quantity or an engine oil system malfunction. If the latter, refer to the engine manufacturer's manual for oil system troubleshooting guide. A grounded wire or permanently closed switch are unlikely because the pre-alarm switch has to operate to arm the shutdown system. However, a double fault is possible and should never be discounted. When all other troubleshooting possibilities have been tried, the double fault should be considered. This could be either— 1. Grounded wire between 1TB11-30 and LOP switch. 2. Grounded wire between TB11-34 and LOP pre-alarm switch. 3. Permanently closed LOP switch. 4. Permanently closed LOP pre-alarm switch. 5. Faulty engine monitor board.
Oil pressure less than 20 psi (138 kPa), oil level low, oil sender issue
1 brand- John Deere: Check oil level, inspect for leaks, restart unit and verify oil pressure, check oil sender
Common questions
What causes low oil pressure shutdown?
Common causes, most-reported first: Low oil level; Oil pressure is less than 20 psi (138 kPa), engine has oil leaks, or oil pressure sender is faulty.; Oil pressure is less than 20 psi, engine has oil leaks.; Oil pressure is less than 20 psi (138 kPa).; Low oil level, Oil leaking from engine, Oil pressure sender; Oil pressure is less than 20 psi (138 kPa), oil level is low, or oil pressure sender is damaged..