DiagnosticsMedium severity

Bobcat M0822 (08-22) Fault Code: Engine Coolant Temperature Out of Range Low

Also shown on the panel as 08-22 · Also called code: M0822: Engine Coolant Temperature Out of Range Low

Engine Coolant Temperature Out of Range Low · ai-assisted, editor-reviewed · Last updated 2026-07-13

TL;DR

M0822, shown on the panel as 08-22, sets when the gateway controller sees less than 0.4 volts on the engine coolant temperature sensor signal circuit with the key switch (run/enter) on. It usually points to a shorted signal wire, a sensor fault, or a wiring/connector problem rather than actual coolant temperature.

Medium severity. M0822 is not a stop-now emergency by itself, but it means the gateway controller is not getting a valid coolant temperature reading. Running without accurate coolant temperature can mask real overheating, so diagnose it before extended operation, especially in hot weather or high-load work.

What does Bobcat error code M0822 mean?

M0822 is set by the gateway controller when it detects the voltage on the engine coolant temperature sensor signal circuit is less than 0.4 volts. This sensor is fed an 8 volt supply through the gateway controller, regulated down to 7.85 volts (±0.05) at the sensor.

The engine coolant temperature sensor works as a variable resistor with an operating range of 500 to 3000 ohms. As coolant gets hotter, sensor resistance rises and signal voltage rises with it. A reading below 0.4 volts looks like a dead short to ground on the signal circuit, or a sensor and wiring problem, rather than a real 'cold coolant' condition.

Because this is a low-side fault on the sensor circuit, the ECM cannot trust the coolant temperature reading it is getting. That can affect cooling fan control, warm-up logic, and any display of engine temperature, so it is worth chasing down even if the machine seems to be running fine.

What triggers a Bobcat M0822 code?

The code sets when the gateway controller measures less than 0.4 volts on the engine coolant temperature sensor signal wire while the key switch (run/enter) is on.

Common causes of M0822

Coolant temperature sensor signal wire (3170 on some harnesses, 3200 on others) shorted to ground
Hydraulic charge pressure sensor supply wire (5190 or 3400 depending on harness) shorted to battery voltage or shorted to ground, which can affect the shared supply circuit
Faulty engine coolant temperature sensor
Faulty hydraulic charge pressure sensor
Gateway controller fault
Moisture, corrosion, or pushed-back pins in the gateway controller connector, the engine coolant temperature sensor connector, the hydraulic charge pressure sensor connector, the engine harness, or the mainframe harness
Intermittent faults from loose connections, corrosion, pushed-back pins, the controller, or the wire harness, alone or in combination, which may not show up if the code is not active during testing

How to troubleshoot Bobcat M0822: first checks

Confirm the key switch is in run/enter and check whether the code is currently active or was only stored, since intermittent faults may not reproduce during testing
Inspect the engine coolant temperature sensor connector and the gateway controller connector for moisture, corrosion, or pushed-back pins
Check the coolant temperature sensor signal wire for chafing or shorts to ground along the engine harness and mainframe harness
Check the hydraulic charge pressure sensor supply wire for signs of a short to battery voltage or to ground, since it shares circuitry relevant to this code
Test the engine coolant temperature sensor resistance across its temperature range and compare against the 500 to 3000 ohm operating range
Verify supply voltage at the sensor connector is close to the expected 7.85 volts (±0.05) from the 8 volt gateway controller supply
If all wiring and sensor checks are good, suspect the gateway controller itself

How the code clears

This code is self resetting. No separate clearing step is listed once the underlying wiring, sensor, or connector problem is repaired.

Affected models and serial ranges

M0822 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

Safety-critical: confirm before use

Electrical safety: stop the engine before inspecting wiring, fuses, connectors, or drive belts, and avoid shorting power terminals. Thresholds, component locations, wire numbers, fuse locations, and reset procedures can vary by model, configuration, and serial number. Confirm them in the service documentation for your exact machine.

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Frequently asked questions

What does Bobcat code M0822 mean?

It means the gateway controller sees a coolant temperature sensor signal voltage below 0.4 volts, which is out of the sensor's normal operating range. This usually indicates a wiring short to ground, a bad sensor, or a connector problem rather than the coolant actually being cold.

Is M0822 the same as panel code 08-22?

Yes. M0822 is the controller code and 08-22 is how it displays on the numeric panel readout.

Can I keep operating with M0822 active?

Short-term operation is usually possible, but the controller cannot verify real coolant temperature while this code is set, so cooling fan control and overheat warnings may not work as expected. It is best to diagnose it before running the machine hard or in hot conditions.

Does M0822 clear itself after I fix the wiring?

Yes, it is listed as self resetting. No separate manual clearing procedure is required once the short, connector issue, or sensor problem is repaired.

Why does the hydraulic charge pressure sensor wiring matter for a coolant temperature code?

On these harnesses the coolant temperature sensor supply and the hydraulic charge pressure sensor supply wire share related circuitry. A short to battery voltage or ground on the charge pressure sensor supply wire can pull down the coolant sensor signal and trigger M0822.

What if the code does not show up when I test the machine?

If M0822 is intermittent and not active during testing, the cause may not be found right away. Likely culprits are loose connections, corrosion, pushed-back pins, the wire harness, or the gateway controller, sometimes in combination.

Which Bobcat machines can show M0822?

M0822 applies across the S510, S530, S550, S570, S590, S630, S650, S750, S770, T550, T590, T630, T650, T750, and T770 model lines, and T870.