The Common Reasons Bobcat M0117 Stays On After a New Filter
Bobcat M0117 won’t clear with a fresh filter? Bobcat lists it beside M0116 and two derate codes, and each points somewhere different on M-Series loaders.
Table of Contents
Bobcat M0117 after a new filter: what it means and what to check
M0117 is Bobcat’s “Air Filter Plugged” service code for M-Series loaders, the S450–S850 and T450–T870. If a new filter didn’t clear it, the controller is still reading restriction, or the switch circuit itself is faulted.
Check these in order: the element part number and seal, the intake path, then the sensor connector. M0116 appearing alongside M0117 points at the circuit, not the filter.
- Machine derated or in limp mode → Section 4
- Codes appearing in pairs → Section 3
- Want the fix confirmed → Section 6
ℹ️ Safety Note: Air filter and sensor access on these loaders means working in the engine compartment, near exhaust components and a cooling fan that stay hot or can move while the engine runs. Shut the engine off, remove the key, and let it cool before opening the rear cover. The information here is for general understanding. Have a certified heavy equipment technician do any electrical diagnosis, following the machine’s Operation & Maintenance manual.
The Bobcat air filter code family, M0116 to M0145
Bobcat’s code list gives the air filter circuit four codes, and the one next to M0117 tells you where to look.
| Code | Applies To | Bobcat description | What it points toward |
|---|---|---|---|
| M0116 | M-Series loader; telehandler (listed as “Air Filter Switch Not Connected”) | Air Filter Not Connected | Switch circuit or connector |
| M0117 | M-Series loader | Air Filter Plugged | Restriction reading at the air cleaner |
| M0144 | M-Series loader; telehandler | Air Filter Derate Level 1 | Engine output being limited |
| M0145 | M-Series loader; telehandler | Air Filter Derate Level 2 | Further engine derate |
Source: Bobcat Diagnostic Service Codes list, Revised 10-20. Verified September 22, 2026. The “What it points toward” column is an editorial reading, not OEM text. Bobcat notes the list was created in 2020 and directs readers to its Machine Diagnostics page for the latest code information.
Serviceability: an owner can check the element and the connector visually. Confirming whether the circuit is faulted needs dealer diagnostics.
AIRF vs. M0117 on the display
A Bobcat dealer advises watching for “AIRF” on skid-steer and compact track loader displays, noting that older machines may show M0117 instead and that a technician can discuss a software update. Older machines can also show the two-part version of this code; see our breakdown of Bobcat 01-17 and M0117 code formats.
R-Series loaders don’t appear against these M01xx entries in the list, so don’t assume the same code applies to them.
Why M0117 stays on with a brand-new filter
A new filter only clears the code if the switch was reading a genuinely loaded filter. Anything else between the intake and the switch keeps it lit.
Wrong element or poor seal
Bobcat writes its O&M manuals to the model and serial number, so parts can change within one model name. For example, aftermarket catalogs list the S650 under both round and square air filter kits. Look up your elements through the Bobcat fault code lookup by serial number, not by model name alone.
M0116 showing too: suspect the sensor or connector
M0116 means the controller sees the air filter switch as not connected. When it cycles with M0117, the filter probably isn’t the problem. Documented owner reports follow this exact pattern (Section 5).
Upstream restriction
Anything restricting airflow before the switch can register as a plugged filter. Documented reports include an intake that pulled together when hot (Section 5). Bobcat’s public code list doesn’t describe the switch’s location, type, or test values; those are in your serial range’s service literature.
Stored vs. active code
Bobcat’s public list doesn’t say whether M0117 clears itself once restriction drops, or whether it needs a reset. Your O&M manual covers this for your serial range.
⚠️ Hazard: Don’t unplug, jumper, or bypass the air filter switch to kill the code. The controller watches for a disconnected switch (that’s what M0116 is), and masking a real restriction lets the engine run on an air supply nobody is monitoring. Have a certified heavy equipment technician test the circuit.
Can you keep running a Bobcat showing M0117?
Bobcat’s public code list doesn’t state whether M0117 on its own is a warning or triggers a derate. What it does show is separate derate codes, M0144 and M0145, so the display tells you when the machine starts limiting power.
- M0117 alone, full power: finish the Section 3 checks before the next shift. Your O&M manual defines what continued operation is allowed.
- M0144 or M0145 showing: the machine is derating because of the air filter circuit. Stop production work and get it diagnosed.
For how M0117 compares with codes that halt the machine outright, see which Bobcat codes actually stop work.
✅ Do This: Ask a certified heavy equipment technician two things. Is the switch reading real restriction or a circuit fault? Is your display software current?
What owners report when M0117 won’t clear
Documented owner reports show a consistent pattern: new filters, a recurring code, and the eventual fix sitting somewhere other than the filter.
| Machine | Series | Reported | What happened | Outcome reported |
|---|---|---|---|---|
| T650 | M | 2019 | Both elements new; M0117 with intermittent M0116 | Service tech suspected the sensor was causing limp mode |
| T770 | M | 2023 | Filters replaced, code reset | M0145 returned after about 2 hours |
| T86 | R | 2023 | Repeated plugged-filter codes, limp mode | Dealer replaced the airbox sensor; codes back after about 5 hours |
| T86 | R | 2023 | Same symptom | Repeated dealer visits; bracket added to keep the intake from pulling together when hot |
| T870 | M | 2023 | Airflow fault | Sensor connector cleaned and reseated |
Sources: HeavyEquipmentForums (Sept 2019), JustAnswer (Oct 2023), Skidsteer Forum (Oct 2023). Checked September 22, 2026.
What the reports don’t prove
These are five self-reported accounts across three threads. None is confirmed by Bobcat, and the T86 posts don’t name the code number. Posters also warned that blocking or modifying the intake would void the warranty, so don’t copy that suggestion.
When M0117 needs a Bobcat dealer or service tool
Once the element, seal, and connector check out, the remaining diagnosis needs tools most owners don’t have.
What the dealer can see that you can’t
For more detailed code descriptions and troubleshooting, Bobcat points owners to Machine IQ Health and Security, available through the Bobcat Owner Portal. A dealer can also check whether your display software is due an update (Section 2). No dated diagnostic price was verified for this article, so get a written quote.
✅ Do This: Ask the dealer three things. Is the fault active or stored? Is the switch or the circuit at fault? Is a software update pending for this serial number?
🧮 Run the Numbers: Weigh lost hours against the dealer’s quote in the Equipment Cost-Per-Hour Calculator. You’ll need the machine’s hourly owning cost, the hours lost, and the quoted diagnostic fee.
Air filter habits that keep M0117 from coming back
Most repeat M0117 trips come from how the filter gets handled, not how often it’s changed.
Don’t open it just to look
A Bobcat dealer advises against opening the air cleaner for quick checks, since each unnecessary opening risks contaminating the engine. Let the display tell you when the filter is loaded. On M-Series loaders, both engine air filters sit under the back cover on top of the machine.
Buy by serial number
Service intervals and filter parts are set in the O&M manual for your serial range. Don’t clean and reuse the inner element unless that manual says it’s permitted.
FAQ
1. What does M0117 mean on a Bobcat?
Bobcat code M0117 means “Air Filter Plugged” on M-Series loaders, the S450–S850 and T450–T870, according to Bobcat’s diagnostic code list.
2. Why does M0117 stay on after a new filter?
M0117 can persist because of a wrong element, a poor seal, an upstream intake restriction, or a faulty air filter switch circuit. Have a technician test the circuit.
3. What is Bobcat code M0116?
Bobcat M0116 means “Air Filter Not Connected.” Seen alongside M0117, it points toward the switch circuit or connector, not the filter itself.
4. Can I keep running my Bobcat with M0117?
Bobcat’s public list doesn’t define M0117’s run limits. If M0144 or M0145 appears, the machine is derating. Check your O&M manual or ask a dealer.
5. What are Bobcat codes M0144 and M0145?
Bobcat lists M0144 and M0145 as Air Filter Derate Level 1 and Level 2 on M-Series loaders and telehandlers, meaning engine output is being limited.
6. What does AIRF mean on a Bobcat display?
A Bobcat dealer says newer loader displays show AIRF, while older machines may show M0117 for the same air filter condition.
7. Where is the air filter on an M-Series loader?
On Bobcat M-Series loaders, the inner and outer engine air filters sit under the back cover on top of the machine, per a Bobcat dealer.
8. How do I clear Bobcat code M0117?
Bobcat’s public code list doesn’t describe clearing M0117. Your serial range’s O&M manual covers it, or a dealer can confirm with diagnostics.
9. Does unplugging the air filter sensor fix M0117?
No. Bobcat’s controller watches for a disconnected air filter switch, reported as M0116, and bypassing it hides real restriction. Have a technician test the circuit.
10. Should I check my Bobcat air filter often?
A Bobcat dealer advises against opening the air cleaner for quick looks, since unnecessary openings can contaminate the engine. Rely on the display.
Where this leaves you
If a new filter didn’t clear M0117, you’ve already ruled out the cheapest cause. The next checks are the part number, the seal, and the connector, then a dealer diagnosis.
- Keep running? Watch for M0144 or M0145, and see which Bobcat codes actually stop work for context.
- Older machine? Confirm which code format your display uses with our 01-17 and M0117 format guide.
- Price the downtime: use the Equipment Cost-Per-Hour Calculator with your hourly owning cost and the dealer’s quote.
- Most important question for your technician: is this real restriction or a circuit fault?
