Powertrain, generic (extended)

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

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

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.

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)

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

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–350
Time0.3–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

egt sensor b1s3

Related codes

P242AP242BP242CP2033P2469

References: gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com, serdia.deutz.com.