P041B: EGR Temperature Sensor B Circuit Range/Performance

EGR temperature sensor B measures the gas temperature in the EGR path – for cooler monitoring, component protection and the EGR model. Whether it sits before or after the cooler depends on the maker: GM diesels have sensor A after and B before the cooler, Ford diesels sensor B after it. Like a coolant sensor it is an NTC, so a low voltage means hot. P041B is its plausibility check. Ford diesels compare it at a cold start, after at least 6 hours off, with two other air temperatures (limit 25 °C, 30 °C with a block heater); GM diesels set the code if it barely changes after 8 hours off and EGR operation. Ford petrol engines list P041B with the electrical checks (5 s). MIL after two trips.

Symptoms

• Check engine light on
• Usually no change in driving
• Substitute value used, EGR cooler check suspended

Most likely causes

• Sensor drifting or sluggish (soot)
• Contact resistance in the connector
• No EGR flow (GM stuck test)
• Comparison sensor (intake or charge air temperature) faulty

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the connector and any vacuum hoses
2. Compare the reading with other engine data while varying the engine speed.
3. Use live data to compare the commanded opening with the actual opening
4. Clean the valve and passages if they are clogged with carbon
5. Test the actuator with the scanner
6. Replace the valve if it still does not follow the command after cleaning

Good to know

• Repair difficulty: easy
• It affects emissions.

What each character of P041B means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 4: Emissions
• 1B: Specific fault in that system

Frequently asked questions

Can I keep driving with code P041B?

You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

What causes code P041B?

The most common causes are: sensor drifting or sluggish (soot); contact resistance in the connector; no EGR flow (GM stuck test).

Related codes

• P041AEGR Temperature Sensor B Circuit
• P041CEGR Temperature Sensor B Circuit Low
• P041DEGR Temperature Sensor B Circuit High
• P040BEGR Temperature Sensor A Circuit Range/Performance
• P040FEGR Temperature Sensor A/B Correlation

Sources

• fordservicecontent.com: obd summary diesel 2023
• fordservicecontent.com: OBD Operations Summary Gasoline 2020 2023
• gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
• gsi.ext.gm.com: 17OBDG04 Engine Diagnostics

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.