P0546 on GMC: How to Diagnose & Fix
Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 1
1 GMC model · 1 documented issue · $800-$2,500 repair
P0546 on GMC by model: symptoms, diagnosis and fix
The cast iron exhaust manifolds on the Duramax diesel engine are prone to cracking and warping due to extreme exhaust gas temperatures and thermal cycling. Cracks typically develop at the manifold-to-head mounting points, causing exhaust leaks that produce a ticking noise on cold starts. The up-pipe connections also warp, allowing soot to blow onto engine components. This issue affects both the LML (2015-2016) and L5P (2017-2024) engines.
Common Symptoms
- Ticking or tapping noise on cold start that fades as engine warms
- Exhaust smell in cab especially at idle
- Soot buildup on engine components near manifold
- Visible cracks in exhaust manifold on inspection
- Slightly reduced fuel efficiency
- Exhaust leak sound under load
How to Fix
Replace the cracked exhaust manifold with OEM or upgraded aftermarket units ($400-$800 per side for parts). PPE and Pacific Performance Engineering make reinforced stainless steel manifolds ($600-$1,200) that resist cracking. New exhaust manifold bolts and gaskets are essential during replacement — always use OEM bolts as they are designed for the thermal expansion. Labor runs 4-8 hours ($600-$1,200) depending on which side. Inspect up-pipes for warping at the same time.
Sources for this issue (1)
P0546 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0546 mean on a GMC?
P0546 stands for "Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 1." This code means the engine computer detected an abnormally high voltage (or out-of-range high signal) from the exhaust gas temperature (EGT) sensor on Bank 1, Sensor 1. The EGT sensor monitors exhaust heat to protect components like the turbocharger, catalytic converter, and diesel particulate filter from overheating. A faulty reading can disable protective strategies and may put the engine into reduced-power mode. On GMC it is documented across 1 model: Sierra 3500HD.
What are the most common causes of P0546?
The most common causes of P0546 are: Faulty exhaust gas temperature sensor, Open or shorted EGT sensor wiring, Corroded or loose sensor connector, Damaged sensor from excessive exhaust heat, Exhaust leak near the sensor, PCM circuit fault. The specific cause varies by vehicle.
How much does it cost to fix P0546 on a GMC?
Published repair estimates on GMC range from $800 to $2,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0546 on a different make?
View P0546 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.