Powertrain, generic (extended)

P20E4 Exhaust Gas Temperature Sensor 2/3 Correlation (Bank 1)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P20E4 covers the pair around the particulate filter: sensor 2 at the filter inlet and sensor 3 at its outlet on bank 1 no longer agree. GM documents the code for the diesel in table 15OBDG04 (also 14OBDG04): after a soak of at least 28,800 s the start-up values of the filter upstream and downstream sensors are compared against a look-up limit, and a larger gap is a Type B fault. Because both sensors steer and protect filter regeneration, a biased one can lead to regenerations that run too cool or too hot. P20E2 covers the pair around the oxidation catalyst, while P2084 and P242B report range faults of a single sensor. The patent US7533519 uses the same inlet/outlet arrangement for its stuck-in-range test. Drivers usually see the MIL and may notice more frequent or aborted regenerations.

Likely causes

Filter inlet or outlet temperature sensor aged by heat cycling
Heat-damaged or corroded sensor connector or lead
Heavy soot or ash deposits on a sensor tip slowing its response

Symptoms

  • Malfunction indicator lamp on
  • Regenerations aborted or happening more often
  • Filter loading warning in some vehicles

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–400
Time0.5–2.5 h

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

Parts involved

exhaust gas temperature sensorwiring harness

Related codes

P20E2P20E3P2084P242BP2031P242A

References: gsi.ext.gm.com, patents.google.com.