Bobcat M0409 (04-09) Fault Code: Engine Oil Pressure Low
Also shown on the panel as 04-09 · Also called Engine Oil Pressure Too Low
Engine Oil Pressure Low · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
M0409 (panel code 04-09) sets when Bobcat's gateway controller sees a signal from the engine oil pressure sensor that reads below the low-pressure threshold set for that machine model. It sets with the key switch (run/enter) on and the engine running above 1400 RPM. Treat it as a real oil pressure warning until proven otherwise, this is not a cosmetic fault.
Critical severity. Low oil pressure at running RPM can cause serious internal engine damage in a short time. Shut the engine down and check oil level and pressure before continuing to operate. Do not run the machine on the assumption the sensor is faulty until you've confirmed oil level and pressure by other means.
What does Bobcat error code M0409 mean?
M0409 is Bobcat's code for Engine Oil Pressure Low or Engine Oil Pressure Too Low. It fires when the gateway controller reads a signal from the engine oil pressure sensor that comes in under the specified low-pressure value programmed for that specific machine model. Because the threshold varies by model, there's no single pressure number that applies across the whole lineup, the controller is comparing the live sensor signal against a model-specific setpoint stored internally.
This code covers a wide range of Bobcat skid-steer and track loader models, including the S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, T770, and T870.
The key point for any operator or tech: this code is telling you the controller believes oil pressure is too low for safe running. Sometimes that's a real mechanical problem, sometimes it's a sensor or wiring fault, but you can't tell which just from the code lighting up. Every case needs a physical check before you write it off as electrical.
What triggers a Bobcat M0409 code?
The code sets when the key switch (run/enter) is on and the engine is running above 1400 RPM, with the gateway controller detecting an oil pressure sensor signal below the specified low-pressure value for that machine.
Common causes of M0409
- Low engine oil level, the most basic and most common cause and the first thing to rule out.
- A problem with the 5-volt supply wire feeding the oil pressure sensor circuit (identified as wire 5140 on some machines and wire 3500 on others, depending on model and harness version).
- General engine problems that actually reduce oil pressure (worn bearings, pump wear, oil pump issues, etc.).
- A failed or failing engine oil pressure sensor.
- A fault in the gateway controller itself.
- Moisture, corrosion, or pushed-back pins in the gateway controller connectors, the engine oil pressure sensor connector, or the mainframe harness.
- Intermittent faults: if the code isn't active at the time of testing, the root cause may not show up right away. Loose connections, corrosion, pushed-back pins, the controller, the wire harness, or some combination of these can all produce an intermittent version of this code.
How to troubleshoot Bobcat M0409: first checks
- Shut the engine down safely and check the engine oil level on the dipstick before doing anything else. Top off if low and recheck for the code.
- Inspect the engine oil pressure sensor connector and the mainframe harness connectors for moisture, corrosion, or pushed-back pins.
- Check the condition of the 5-volt supply wire to the sensor (wire 5140 or wire 3500 depending on model) for damage, chafing, or poor connection.
- With the key on and engine running above 1400 RPM, verify whether the code is active or only stored, this tells you if you're chasing a live fault or an intermittent one.
- Inspect the engine oil pressure sensor itself for damage or contamination, and test or swap it if available, since a failed sensor can report low pressure that doesn't actually exist.
- If oil level and wiring check out, look deeper at engine condition (oil pump, bearings) since real mechanical oil pressure problems are on the cause list and can't be ruled out by electrical checks alone.
- Check the gateway controller's connectors for the same moisture, corrosion, or pushed-back pin issues listed for the sensor and harness.
How the code clears
This code is self resetting. No separate clearing step is listed. Once the underlying cause is corrected (oil level restored, wiring or connector repaired, sensor or controller replaced as needed) the code should clear on its own once the oil pressure signal is back above the model's threshold.
Affected models and serial ranges
M0409 appears in our records across 16 Bobcat models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| S510 | SN A3NJ11001-99999, SN A3NK11001-99999, SN ATZC11001-ATZC99999 |
| S530 | SN A7TV11001-99999, SN ATZD11001-99999 |
| S550 | SN A3NK11001-A3NL99999, SN A3NM11001-99999 |
| S570 | SN A7U711001-799999, SN A7U811001-899999 |
| S590 | SN ANMN11001-99999, SN ANMP11001-99999 |
| S630 | SN A3NT12370-99999, SN A3NU11001-11111, SN A3NU11112-99999 |
| S650 | SN A3NV11001-13098, SN A3NV13099-99999, SN A3NW11001-11248, SN A3NW11249-99999 |
| S750 | SN A3P211001-299999 |
| S770 | SN A3P411001-99999 |
| T550 | SN A7UJ11001-AJZV12276 |
| T590 | SN ALJU11001-999999, SN B37811001-999999, SN B3Z711001-999999 |
| T630 | SN A7PU11001-11663, SN A7PU11664-99999 |
| T650 | SN A3P012214-099999, SN A3P111242-199999 |
| T750 | SN ANKA11001-A99999 |
| T770 | SN A3P811001-899999, SN A3P911001-999999 |
| T870 | SN A3PG11001-99999, SN A3PH11001-99999 |
Frequently asked questions
What does Bobcat code M0409 mean?
It means the gateway controller detected an engine oil pressure sensor signal reading below the low-pressure value set for that specific machine model, while the key switch is on and the engine is running above 1400 RPM. It can point to a real low oil pressure condition or to a sensor/wiring fault.
Is it safe to keep running the machine with M0409 active?
No. Low oil pressure at running RPM risks serious engine damage. Shut down and check the oil level and connectors before resuming work. Don't assume it's just a sensor issue until you've physically verified oil level and condition.
What's the first thing to check for M0409?
Check the engine oil level first. Low oil level is listed as a direct cause and is the quickest thing to rule out or confirm.
Does M0409 clear itself after a repair?
Yes, it's listed as self resetting. Once the actual cause is fixed and oil pressure reads correctly, the code clears without a separate manual reset procedure.
Why do some Bobcat manuals list wire 5140 and others wire 3500 for this code?
The 5-volt supply wire number to the oil pressure sensor differs depending on model and harness version. Some documentation references wire 5140, other model variants reference wire 3500. Both are part of the same sensor supply circuit.
Can a bad connector cause M0409 even if the engine oil pressure is fine?
Yes. Moisture, corrosion, or pushed-back pins in the gateway controller connectors, the oil pressure sensor connector, or the mainframe harness can all cause a false low-pressure signal even when actual oil pressure is normal.
What if the M0409 code only shows up sometimes?
An intermittent M0409 that isn't active during testing can be harder to pin down. Likely causes include loose connections, corrosion, pushed-back pins, the controller, the wire harness, or a combination of these. Recheck connectors and wiring carefully even if the code isn't currently active.