Exhaust Gas Pressure Sensor Circuit - Voltage Below Normal
What does CUMMINS-2787 mean?
The CUMMINS-2787 (Cummins) diesel fault code means: Exhaust Gas Pressure Sensor Circuit - Voltage Below Normal. This is a moderate severity code.
Common Symptoms
- Power loss especially under load
- Turbo lag or sluggish acceleration
- Black smoke under acceleration
- Higher than normal EGT
- Check Engine Light on
Probable Causes (Ranked by Likelihood)
- EGR valve carbon-seized in partially open position Very Likely
- Failed EGR position sensor Likely
- Clogged EGR cooler restricting flow Likely
- VGT actuator stuck from carbon or corrosion Possible
- Leaking EGR cooler causing coolant loss Possible
Step-by-Step Diagnostic Procedure
Connect INSITE and command the EGR valve through its full range while monitoring position feedback for smooth response.
Remove EGR valve and inspect for carbon buildup; soak in carbon cleaner and reinstall or replace if deeply fouled.
Measure VGT actuator voltage and calibration via INSITE output test -- command 0%/50%/100% and verify position.
Inspect EGR cooler for internal leakage (coolant loss or steam from exhaust) -- pressure test if suspect.
Check turbocharger for shaft play, oil leaks at seals, and smooth spool under throttle.
Verify EGR differential pressure and temperature sensors read rational values on INSITE data list.
Frequently Asked Questions
What is Cummins fault code 2787?
Cummins fault code 2787 indicates: Exhaust Gas Pressure Sensor Circuit - Voltage Below Normal. It is a moderate-severity fault in the aftertreatment or emissions system.
Can I drive with Cummins fault code 2787?
Yes, short-term driving is typically safe with fault 2787, 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 2787?
Repair cost is approximately $250-$700 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.