Powertrain, generic (extended)

P2B0B Cold Start Cylinder 4 Injection Pulse Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2B0B covers cylinder 4 during the cold-start strategy and in GM's tables belongs to four-cylinder and larger engines. GM's 2025 four-cylinder table sets the window via P2B95 differently from the three-cylinder: catalyst below 400 °C, 450–2,800 rpm, pedal up to 35 % and less than 100 s run time, so the test may continue while pulling away. The cylinder code itself is Type B after 50 to 100 samples. GM bulletin 20-NA-230 (2021 Malibu, Equinox, Terrain) treats P2B0B as a software issue solved by a new calibration; engineering information PIE0808 for the 2023–2024 Colorado and Canyon 2.7 L names it among codes still being investigated, with a harness check and fuel rail connector reseat. Warm-engine faults on this cylinder are P2B03.

Likely causes

ECM calibration needing an update (GM bulletin 20-NA-230)
Harness damage or poor contact at the fuel rail connector (GM 2.7 L)
Cylinder 4 injector sluggish at low temperature

Symptoms

  • Warning lamp after cold starts
  • Possibly slightly uneven running during the first minute

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–900
Time0.3–4 h

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

Parts involved

fuel injector cylinder 4injector wiringengine control module

Related codes

P2B03P2B0AP2B0CP2B95P0204P0304

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.