GM Duramax · Exhaust Gas Temperature Sensor Bank 1 Sensor 2Medium

GM Duramax P2033: EGT Sensor Circuit Low Bank 1 Sensor 2

P-Code P2033 (FMI N/A) — Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 2

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Quick Answer

P2033 means the downstream EGT sensor circuit voltage is lower than expected. Inspect for harness chafe and connector damage before replacing the sensor, since regen control depends on accurate readings.

Overview: GM Duramax P-Code P2033

ProfessionalDieselRepair.com treats Duramax P2033 as an aftertreatment wiring problem until proven otherwise. When Bank 1 Sensor 2 drops out, the ECM loses confidence in exhaust temperature downstream of the turbo and may withhold DPF regeneration.

Repair Snapshot

Time

1 - 3 Hours

Difficulty

Intermediate

Parts Cost

$75 - $250

Dealer Labor

$450+

Tools Required

  • Diesel Laptops
  • Noregon JPRO
  • Multimeter
  • Heat Gun

What P-Code P2033 Means

P2033 on GM Duramax diesel indicates the downstream EGT sensor circuit is reading lower voltage than expected. The ECM uses this sensor for DPF regen control and over-temperature protection, so a faulty signal can block regens or set companion aftertreatment codes.

Symptoms Drivers Notice

  • Check engine light
  • Reduced or blocked DPF regen attempts
  • Companion SCR or DPF efficiency codes over time
  • Exhaust temperature gauge or data may read incorrectly
  • No immediate power loss in most cases

Most Likely Root Causes

Chafed or shorted EGT sensor harness

Common

Rubbing against frame or heat shields shorts the signal wire to ground, producing a low circuit reading.

Failed downstream EGT sensor

Common

Internal element degradation sends a stuck-low voltage signal even when exhaust is hot.

Corroded connector at the sensor

Occasional

Moisture intrusion increases resistance and pulls voltage below the PCM threshold.

Common Misdiagnoses (Don't Waste Parts)

Replacing the DPF or SCR components when only EGT data is missing

Why it happens: Regen failures prompt techs to chase aftertreatment hardware.

Do this instead: This is a parts-cannon mistake - restore valid EGT readings first. Many regen blocks clear once the sensor circuit is repaired.

Swapping upstream and downstream sensors without checking part numbers

Why it happens: Both are EGT sensors and look similar.

Do this instead: Confirm Bank 1 Sensor 2 location and wiring continuity on the correct circuit only.

Master Tech Commentary

Mechanic's Notes

ProfessionalDieselRepair.com reminder: downstream EGT faults on L5P and earlier Duramax trucks often trace to harness chafe at the frame crossmember, not a failed sensor. Wiggle-test the harness before ordering parts.

Step-by-Step Diagnostic Procedure

  1. Step 1: Scan with Diesel Laptops or Noregon JPRO and monitor Bank 1 Sensor 2 EGT live data compared with upstream sensors during idle warm-up.
  2. Step 2: Inspect the sensor connector for melted pins, corrosion, or oil contamination near the exhaust aftertreatment pipe.
  3. Step 3: Backprobe the circuit for proper reference voltage and ground, checking for short-to-ground on the signal wire.
  4. Step 4: Verify sensor resistance and response by gently heating the tip with a heat gun while watching live data if service information allows.
  5. Step 5: Replace the sensor only after confirming wiring integrity, since chafed harnesses near the transfer case are a known Duramax failure point.

Live Data & Freeze-Frame Tips

Compare all EGT sensors during a cold start warm-up. A sensor that stays flat while others rise indicates a circuit or element fault on that specific channel.

Safety Warnings

  • Allow exhaust to cool before disconnecting sensors.
  • Support the vehicle safely if working beneath the aftertreatment pipes.
  • Avoid contact with hot exhaust components after recent driving.

When to Limp In vs Tow

Not usually required unless companion codes have already placed the truck in a severe derate.

Prevention Tips for Fleets & Owner-Operators

  • Re-route or protect harnesses if chafe marks are visible during service.
  • Apply dielectric grease to connectors after cleaning corrosion.
  • Address exhaust leaks that soak nearby wiring with heat and moisture.

Related Fault Codes

P2032

EGT circuit low on Bank 1 Sensor 1, a related upstream temperature circuit fault.

P0544

EGT sensor performance fault that may appear if temperature readings become implausible.

Frequently Asked Questions

Will P2033 stop DPF regen?

It can. The ECM may inhibit regen if it cannot verify downstream exhaust temperature.

Is this the same sensor as P2032?

No. P2033 is Bank 1 Sensor 2 downstream, while P2032 refers to a different sensor position.

Can I drive with this code?

Usually yes for daily driving, but fix it soon to avoid soot buildup from missed regens.

How much does the sensor cost?

Most downstream EGT sensors run under $250 in parts, while harness repairs can be cheaper if chafe is the cause.

Do I need a dealer scan tool?

Diesel Laptops or Noregon JPRO can read live EGT data and clear the code after repair on most Duramax years.

Could a blown fuse cause P2033?

Yes, if the sensor shares a fused supply circuit. Check power and ground before replacing the sensor.

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