Diagnostic article Generic OBD-II
P245B: EGR bypass performance is checked through temperature response
Ford diesel P245B uses a downstream EGR temperature-gradient test during a qualified intrusive monitor.
Read before applying this article
Documented application
Ford 2023–2024 diesel OBD summary, revised August 25, 2023; these are documented monitor examples, not confirmed fitment or universal thresholds for every vehicle carrying this generic code.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P245B names EGR cooler bypass control circuit range/performance. Ford’s diesel summary describes an intrusive temperature-response monitor, with a failure boundary of downstream EGR temperature gradient below 3°C per second. The broad circuit label therefore does not establish that an electrical continuity fault was detected.
Stable conditions make the response meaningful
The monitor runs once per driving cycle when qualified. Closed-loop EGR is required, and the bypass cooling command is evaluated during monitor pre-release. Coolant, speed, torque, EGR flow, and several rates of change are constrained so that unrelated operating transients do not dominate the temperature response.
Ford provides different speed and torque windows for 6.7L and 3.0L examples. The source lists detection as immediate after the monitor’s qualifying setup; that should not be read as “any cold temperature reading instantly sets P245B.”
Temperature movement is different from absolute temperature
A gradient assesses change over time. One downstream temperature value without its timing cannot demonstrate whether the 3°C/s response boundary was met. This also differs from the P2457 undercooling comparison against coolant temperature elsewhere in the document.
Useful verification retains the intrusive test state, command context, and temperature timeline. The summary does not provide a complete actuator-command sequence or identify a replacement part. A weak response is evidence to investigate with the correct vehicle procedure, not automatic proof of a failed bypass motor, cooler blockage, or temperature sensor.
Source and applicability
This explanation follows Ford’s 2023–2024 diesel OBD summary. Match the vehicle’s engine and calibration before applying these monitor values; a generic code alone does not establish fitment. Ford PDF, page 39.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
EGR Cooler Bypass Control Circuit Range/Performance Bank 1
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT