Hydraulic Reservoir Level Switch Reports Low Fluid
The CAT-SKIDSTEER-HYDRAULIC-OIL-LEVEL-LOW (CAT Skid Steer) diesel fault code means: Hydraulic Reservoir Level Switch Reports Low Fluid. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- Top-off fluid only: $20-$60 DIY. Hose or fitting replacement: $80-$250 DIY or $150-$400 at a shop. Cylinder seal kit: $200-$600 parts plus 2-4 hours labor at a dealer. Level switch replacement: $40-$120 parts, easy DIY swap.
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Common Symptoms
- Cab display shows E1418 or a hydraulic oil level warning icon
- Loader arms feel sluggish or respond slower than normal when lifting
- Steering becomes stiff or pulls to one side under load
- Attachments like augers or buckets lose power or stall mid-cycle
- Machine may derate hydraulic flow automatically to protect the pump
- Visible hydraulic oil puddle or wet streaks on the frame, hoses, or quick couplers
- Hydraulic oil level sight glass on the reservoir shows below the MIN mark
Probable Causes (Ranked by Likelihood)
- External hydraulic oil leak from a hose, fitting, or quick coupler Very Likely
- Worn or damaged hydraulic cylinder seals allowing oil to bypass internally or weep externally Likely
- Loose or cracked hydraulic tank return line or suction hose connection Likely
- Level switch failure or stuck float giving a false low reading when fluid is actually adequate Possible
- Oil consumed through a leaking hydraulic pump shaft seal Possible
- Reservoir was never filled to the correct level after recent service or filter change Possible
- Wiring fault or open circuit in the level switch harness sending a false signal to the ECM Less Likely
Step-by-Step Diagnostic Procedure
Park the machine on level ground, lower the loader arms fully, shut the engine off, and wait 5 minutes for oil to settle back into the reservoir before checking the sight glass.
Inspect the sight glass on the hydraulic reservoir. Oil should be visible between the MIN and MAX marks. If it is below MIN or not visible at all, you have a confirmed low-level condition, not a sensor fault.
Walk the entire machine and look for wet oil on hoses, quick coupler bodies, cylinder rod seals, the boom pivot area, and underneath the frame. A flashlight helps. Even a slow seep will show as a shiny wet streak or dirt sticking to a wet surface.
Check the hydraulic filter housing and drain plug for seepage. A recently changed filter that was not tightened fully is a common source of slow leaks on rentals.
If no external leak is visible but the level is genuinely low, top off with CAT HYDO Advanced 10 (or the fluid spec on the reservoir cap) to the MAX mark, restart, cycle the arms and attachment several times, then recheck the sight glass. A fast drop confirms an active leak.
If the oil level looks correct at the sight glass but the E1418 code persists, locate the hydraulic level switch on the reservoir (typically a float switch on the side or top of the tank). Unplug the connector and check for corrosion or damage. Use a multimeter to verify continuity through the switch with oil present. A switch that reads open when submerged is faulty.
Inspect the wiring harness from the level switch back toward the cab. Look for chafed insulation, pinched wires at frame edges, or corroded terminals. Repair or replace damaged sections before condemning the switch.
If the leak is at a hydraulic cylinder, boom, or inside the final drive, that repair requires disassembly. At that point, contact your CAT dealer or rental yard service team. CAT ET connected to the J1939 service port can confirm whether the ECM is reading an actual switch-open signal or a wiring fault.
Frequently Asked Questions
What does CAT code E1418 or Hydraulic Oil Level Low mean on my skid steer?
It means the float switch inside the hydraulic reservoir is detecting fluid below the minimum safe level. The ECM reads that signal and flags the warning so you stop before running the pump dry. Running a hydraulic pump with low oil will destroy it fast and expensively.
Can I keep using the machine with this code active?
Short answer: no. You can limp it a short distance to a safe parking spot, but you should not keep working. Low hydraulic oil causes erratic steering and loader response, which is a safety hazard. It also overheats and starves the pump. Stop, find the leak or low level, and correct it before running the machine again.
How much does it cost to fix a hydraulic oil level low fault?
If it is just low fluid with no active leak, topping off costs $20-$60 for oil. A leaking hose or fitting is $150-$400 at a shop. A cylinder seal job runs $400-$900 or more at a dealer depending on which cylinder is leaking. A bad level switch is a $40-$120 part you can swap yourself with basic tools.
Could it be a bad sensor giving me a false warning?
Yes, but check the sight glass first. If the oil level looks correct and there is no visible leak, then a faulty level switch or wiring issue is likely. Unplug the switch connector and check continuity with a multimeter. A failed switch is a relatively cheap and easy fix compared to a real oil leak.