Auxiliary Temperature 2 High - Warning
The CUMMINS-299 (Cummins) diesel fault code means: Auxiliary Temperature 2 High - Warning. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $150-$500
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Common Symptoms
- Engine temperature or pressure abnormal
- Possible engine derate or shutdown
- Dash warning lamp illuminated
- Gauges reading outside normal range
- Audible engine change (knock, ticking, or hiss)
- Overheat warning alarm sounding
Probable Causes (Ranked by Likelihood)
- Actual mechanical issue (low oil, coolant, temp) Very Likely
- Failed sensor falsely reporting Likely
- Cooling system issue (fan, radiator, pump) Possible
- Head gasket or combustion gas leak Possible
- Obstructed airflow at charge air cooler Less Likely
Step-by-Step Diagnostic Procedure
Verify the physical condition indicated by fault 299 -- for temperature codes, confirm with an IR thermometer; for pressure codes, use a mechanical gauge.
Compare mechanical reading to sensor reading on INSITE -- if they disagree, sensor or wiring is faulty.
Inspect the mechanical system (cooling, oil, fuel supply) for the underlying issue reported by the sensor.
Check engine fan operation, coolant level, and radiator condition for temp-related codes.
If mechanical reading confirms the fault, repair the underlying system before clearing codes -- clearing without fix will cause fault return and potential engine damage.
Frequently Asked Questions
What is Cummins fault code 299?
Cummins fault code 299 indicates: Auxiliary Temperature 2 High - Warning. It is a low-severity fault affecting engine mechanical condition.
Can I drive with Cummins fault code 299?
Yes, short-term driving is typically safe with fault 299, but the fault will illuminate the Check Engine Light and must be diagnosed soon. Monitor for power loss, unusual noises, or gauge changes and pull over if conditions worsen.
How much does it cost to fix Cummins fault 299?
Repair cost is approximately $150-$500 including parts, labor, and any dealer programming required. DIY repairs (sensor replacement) fall at the low end; pump, aftertreatment, or ECM work falls at the high end and usually requires INSITE diagnostic software.
Sources
This page is built from documented references. Verify against your own service info before repair work.