P04D1: EGR Temperature Sensor C Circuit High

Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. The code standard allows up to four EGR temperature sensors, A to D – for example before and after the cooler, or in the high- and low-pressure circuits; which is which depends on the maker. Sensor C is the third of them, usually an NTC whose low voltage means hot. P04D1 means its signal voltage is above the upper limit – extremely cold, or more often an open sensor, signal or ground line, or a short to 5 V. Besides FCA, GM documents it on the 3.0-litre Duramax LM2 of 2020–21, where it is called EGR temperature sensor 2; if the diagnosis leads to the engine module, module and sensor are replaced together. For sensor B Ford diesels use above 4.95 V.

Symptoms

• Check engine light on
• Usually no change in driving (EGR on a substitute value or off)
• Possibly EGR flow or cooler codes (P0401, P2457)

Most likely causes

• Signal or ground line open, connector off or corroded
• Sensor open internally (element broken)
• Signal shorted to 5 V or positive
• Engine module input

What to check, in order

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

1. Check the connector and any vacuum hoses
2. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
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: medium
• It affects emissions.

What each character of P04D1 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 4: Emissions
• D1: Specific fault in that system

Frequently asked questions

Can I keep driving with code P04D1?

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 P04D1?

The most common causes are: signal or ground line open, connector off or corroded; sensor open internally (element broken); signal shorted to 5 V or positive.

Related codes

• P04CEEGR Temperature Sensor C Circuit
• P04D0EGR Temperature Sensor C Circuit Low
• P04CFEGR Temperature Sensor C Circuit Range/Performance
• P04D2EGR Temperature Sensor C Circuit Intermittent/Erratic
• P040DEGR Temperature Sensor A Circuit High
• P041DEGR Temperature Sensor B Circuit High

Sources

• static.nhtsa.gov: MC 10201272 9999
• static.nhtsa.gov: MC 10209606 9999
• static.nhtsa.gov: MC 10069340 0335

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.