P242D: Exhaust Gas Temperature Sensor Circuit High (Bank 1 Sensor 3)

P242D is the mirror case of P242C: bank 1 probe 3 reports more than its plausible maximum, typically because the circuit is open or touches a supply. GM's 2020 diesel tables trigger above 900 Ω after 10 of 20 samples, the 3.0 L LZO above 100 MΩ for an analog probe or above 1,289.85 °C for a digital one; both tables rate it Type A, so the MIL comes on in the first faulty trip. Ford's 2023 diesels react to more than 2.66 V. Deutz describes P242D-00 as a short to battery. Stellantis lists P242D among the exhaust sensor codes of the 2025–2026 Ram 2500/3500 and asks technicians to check battery voltage first and to identify each sensor by name rather than number. Usually the fix is a connector, a harness repair or the sensor itself.

Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.

Symptoms

• MIL on in the first faulty trip (GM Type A)
• Sensor 3 shows an implausibly high temperature or the maximum value
• Regeneration and DEF dosing restricted

Most likely causes

• Open signal or return wire, broken by heat or vibration
• Connector unplugged or corroded
• Signal wire shorted to a supply voltage
• Low battery voltage during diagnosis (Ram 2025–2026 note)

What to check, in order

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

1. Read the soot load and differential pressure with a scanner
2. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
3. Check the differential pressure sensor's hoses
4. Check the temperatures before and after the filter
5. Fix any fuel injection or EGR codes before regenerating
6. Perform a regeneration while driving or at a repair shop when the diagnosis allows it

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P242D means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 4: Emissions
• 2D: Specific fault in that system

Frequently asked questions

Can I keep driving with code P242D?

If the light is on steadily, take a highway drive or go to a repair shop soon. If the car is in limp mode or the light is flashing, do not push the engine.

What causes code P242D?

The most common causes are: open signal or return wire, broken by heat or vibration; connector unplugged or corroded; signal wire shorted to a supply voltage.

Related codes

• P242AExhaust Gas Temperature Sensor Circuit (Bank 1 Sensor 3)
• P242BExhaust Gas Temperature Sensor Circuit Range/Performance (Bank 1 Sensor 3)
• P242CExhaust Gas Temperature Sensor Circuit Low (Bank 1 Sensor 3)
• P2033Exhaust Gas Temperature Sensor Circuit High (Bank 1 Sensor 2)
• P2469Exhaust Gas Temperature Sensor Circuit High (Bank 2 Sensor 3)

Sources

• gsi.ext.gm.com: 20OBDG04 Diagnostics
• gsi.ext.gm.com: 25OBDG04B
• fordservicecontent.com: obd summary diesel 2023
• serdia.deutz.com: DTCList EMRL1 MainECU EN

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.