P0545 on the 6.7L Cummins is an exhaust gas temperature (EGT) sensor circuit low input fault. The 6.7L uses several EGT sensors along the exhaust and aftertreatment system so the ECM can protect the turbo, control regeneration, and manage the DPF and SCR temperatures. P0545 sets when the ECM reads one EGT sensor's signal too low, indicating a short to voltage on some designs, a wiring fault, or a failed sensor reading implausibly.
EGT data is important for aftertreatment and turbo protection, so a faulty reading can disrupt regeneration and trigger reduced power. P0545 is an electrical circuit code, which points at the sensor, its wiring, and the connector rather than at an actual exhaust temperature problem. Because EGT sensors live in a hot, harsh environment, wiring and connector damage are common, so verifying the circuit first is the right approach.
What P0545 means
An EGT sensor is a thermocouple or thermistor whose signal the ECM converts to a temperature. P0545 sets when that signal reads at the low end of the scale, which the ECM interprets as an implausibly low or invalid reading. Depending on the circuit design it can indicate a short, an open, or a failed sensor, and it points at the sensor and its wiring rather than at true exhaust temperature.
Common causes
- Damaged or chafed EGT sensor wiring from heat
- Corroded or loose EGT sensor connector
- Short or open in the sensor circuit
- Failed EGT sensor reading implausibly low
- Poor ground or reference to the sensor
Symptoms
- Check engine light with P0545 stored
- Regeneration problems or a regen warning
- Reduced power or a derate in some cases
- Implausible EGT reading in scan data
- Companion EGT or aftertreatment codes
How to diagnose it
Identify which EGT sensor the code addresses, then view all EGT readings with a scan tool with the engine cold; they should read close to ambient and to each other. A sensor reading far below the others confirms the fault. Inspect that sensor's connector and wiring for heat damage, chafing, and corrosion, since the exhaust environment is harsh. Back-probe to confirm the reference and ground. Check the circuit for a short or open, and measure the sensor if a specification is available.
How to fix it
Repair heat-damaged or chafed wiring and clean or replace a corroded connector first, since wiring damage is common in the exhaust environment. Confirm a clean ground and reference. If the wiring checks good but the sensor reads implausibly, replace that EGT sensor. After the repair, clear the code, confirm all EGT sensors read plausibly cold and respond as the engine warms, and verify regeneration operates. For EGT sensors and connectors for your 6.7L Cummins, contact sales@coredieselparts.com.
Frequently asked questions
Which EGT sensor does P0545 refer to?
The 6.7L uses several EGT sensors. P0545 addresses a specific circuit; use your scan data and service information to identify which sensor so you inspect the correct location.
Can P0545 affect regeneration?
Yes. The ECM uses EGT data to run and monitor regeneration. A faulty low reading can disrupt regen strategy and, in some cases, trigger reduced power until repaired.
Is P0545 the sensor or the wiring?
Both are possible, but the hot exhaust environment makes wiring and connector damage common. Inspect and repair the circuit first, then replace the sensor if it still reads implausibly.
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