Diesel Trouble Codes

P203F — Exhaust Gas Temperature Sensor Circuit Range/Performance Bank 1 Sensor 2 (6.7 Cummins (SCR / DEF))

Exhaust Gas Temperature Sensor Circuit Range/Performance Bank 1 Sensor 2

Updated September 2, 2026

What it means

The powertrain control module has detected that the exhaust gas temperature sensor circuit for bank 1 sensor 2 is reporting a signal outside the expected range or is performing inconsistently. On the 6.7L Cummins 2013–present SCR/DEF platform, this code is defined as an exhaust gas temperature sensor circuit range/performance fault for bank 1 sensor 2.1

Most likely causes

  1. Exhaust gas temperature sensor Bank 1 Sensor 2 electrical fault or internal failure — Open/short in sensor wiring, connector corrosion, or sensor element drift causing out-of-range or erratic temperature readings.1
  2. Wiring harness chafing/heat damage in exhaust area — Exhaust heat and vibration can damage the EGT sensor harness, leading to intermittent or out-of-range signals.1
  3. PCM signal processing anomaly — The control module interprets a good sensor signal as out of range due to internal reference or software issue.1

How to diagnose

  1. Verify code and freeze frame data; confirm P203F is present and note engine conditions at set.
  2. Inspect EGT sensor Bank 1 Sensor 2 connector and wiring for heat damage, oil contamination, corrosion, and proper routing.
  3. Check sensor supply/reference voltage and ground at the connector per service information; compare to expected values.
  4. Monitor live EGT data for Bank 1 Sensor 2 during idle and controlled load; look for implausible, stuck, or erratic readings versus adjacent EGT sensors.
  5. Perform sensor resistance/characteristic check at known temperatures if supported; compare to specification.
  6. Inspect exhaust system for leaks, modifications, or component replacement that could affect sensor exposure or heat profile.
  7. Clear codes and road test to confirm repeatability; review freeze frame for conditions that trigger the range/performance fault.

Parts and tools you may need

Rough cost and difficulty

Parts and labor vary by model year and location. Diagnostic time is typically 0.5–1.5 h; sensor replacement labor varies with access. Obtain a quote from a qualified shop.

When to see a pro

If the fault persists after electrical inspection, or if multiple exhaust/emissions codes appear, have a qualified diesel technician diagnose the EGT circuit and exhaust system. Do not attempt repairs on high-temperature exhaust components without proper training and safety equipment.

Sources

  1. Curated DTC seed — 6.7 Cummins (SCR / DEF) (curated) ↩︎ ↩︎ ↩︎ ↩︎