Trimble ERR002 Error: What It Means and How to Fix It

Applies to: R8, R10, SPS986, R12

What Does ERR002 Mean?

ERR002 on Trimble receivers indicates significant multipath — a condition where GPS/GNSS signals arrive at the antenna after reflecting off nearby surfaces (buildings, vehicles, metal structures) in addition to arriving directly from the satellite. The receiver detects the timing discrepancy between direct and reflected signals and flags multipath as a quality issue.

Multipath degrades position accuracy. Even with a full RTK fix, heavy multipath can introduce errors of several centimeters to decimeters. ERR002 is Trimble's receiver telling you that its position solution may be less reliable than the reported accuracy suggests. In tight tolerance work (control surveys, machine control calibration), multipath errors can cause real problems.

Common Causes of ERR002

• Working near large reflective surfaces — metal buildings, concrete walls, vehicles, chain-link fencing
• Antenna positioned too close to the ground — signals reflecting off the ground surface near the antenna
• Tall structures surrounding the work area creating a 'canyon' effect where signals arrive from multiple reflected paths
• Antenna mounted near the cab or boom of machinery — metal vehicle surfaces are powerful reflectors
• Tree canopy causing signal scattering — wet foliage is particularly reflective

How to Fix Trimble ERR002 — Step by Step

1. Move away from large reflective surfaces. Even 10-15 feet of additional separation from a metal building significantly reduces multipath.
2. Raise the antenna height if possible — getting the antenna higher above ground-level reflectors reduces multipath from ground bounce.
3. Wait for the multipath indicator to drop in Trimble Access (Survey > Point Details shows multipath level). If it's a temporary condition, waiting 30-60 seconds may be sufficient.
4. Use a ground plane (choke ring antenna accessory) to reduce ground multipath — this is effective for control point work but less practical for stakeout.
5. If in a difficult environment, flag the position as 'observed with multipath warning' rather than accepting the coordinate uncritically.
6. For critical control work, reobserve from a different antenna location and compare positions — if they agree within tolerance, multipath wasn't significant.

When to Send It In for Service

ERR002 is an environmental condition, not a hardware fault. No service needed.

Preventing ERR002 in the Future

Plan antenna locations away from large reflective structures. Use quality dual-frequency antennas which have better multipath rejection than single-frequency units. For control surveys, choose observation times when satellites are at higher elevation angles (above 20 degrees) — lower-elevation satellites produce worse multipath.

Related Error Codes

Trimble Gps Error Err001 | Trimble Gps Error Err003 | Trimble Gps Error Err020