What is a catalytic converter and how do you diagnose and repair it?

A catalytic converter is an emission control device that reduces certain pollutants. There are two types of converters: an oxidation catalyst that reduces hydrocarbons and carbon monoxide, and a reduction catalyst that reduces oxides of nitrogen. Vehicles are equipped with two three-way catalysts that can reduce all three pollutants. Whenever you raise the vehicle to service underbody components, inspect the converter for leaks, corrosion, dents, and other damage. The easiest way to check for a restricted converter is to use a vacuum gauge to diagnose the effect of a blocked exhaust on the intake vacuum. To remove the converter, raise the vehicle and place it securely on jack stands, disconnect the electrical connectors for the upstream and downstream oxygen sensors, remove all four sensors, remove the nuts at each of the upper flanges that secure the front exhaust pipe assembly to the exhaust manifold flanges, remove the nuts that secure the rear flange of the front exhaust pipe assembly to the rest of the exhaust system, and remove the front exhaust pipe assembly. To install the converter, coat the threads of the nuts and bolts with an anti-seize compound to facilitate future removal and tighten the nuts that secure the front exhaust pipe assembly to the exhaust manifold and to the rest of the exhaust system securely.

Genuine GMC Sierra Catalytic Converter

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64 Catalytic Converters found

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GMC Sierra 3Way Catalytic Convertor Assembly (W/Exhaust Pipe)
Part Number: 23486656
$1838.28 MSRP: $2760.00
You Save: $921.72 (34%)
Ships in 1-3 Business Days
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Product Specifications
- Other Name: Converter Assembly, 3Way Catalytic(W/Exhaust Pipe); Catalytic Converter, Converter & Pipe
- Replaced by: 19420288
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2016-2019 GMC Sierra | 1500 CREW CAB, 1500 CREW CAB STANDARD BOX, 1500 DOUBLE CAB STANDARD BOX, 1500 REGULAR CAB LONG BOX, 1500 REGULAR CAB STANDARD BOX, CREW CAB 1/2 TON | 8 Cyl 5.3L
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GMC Sierra 3Way Catalytic Convertor Assembly (W/ Exhaust Manifold P
Part Number: 25904628
$1530.31 MSRP: $2996.63
You Save: $1466.32 (49%)
Ships in 1-3 Business Days
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Product Specifications
- Other Name: Converter Assembly, 3Way Catalytic (W/ Exhaust Manifold P; Catalytic Converter, Converter & Pipe
- Replaced by: 19418939
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2007-2008 GMC Sierra | CREW CAB 1/2 TON, EXTENDED CAB 5'8" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON, EXTENDED CAB 8' BOX 1/2 TON, REGULAR CAB 6'6" BOX 1/2 TON, REGULAR CAB 8' BOX 1/2 TON | 6 Cyl 4.3L, 8 Cyl 4.8L, 8 Cyl 5.3L, 8 Cyl 5.3L Flex, 8 Cyl 6.0L
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GMC Sierra 3Way Catalytic Convertor Assembly (W/ Exhaust Manifold P
Part Number: 20854453
$1724.85 MSRP: $2690.39
You Save: $965.54 (36%)
Ships in 1-3 Business Days
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Product Specifications
- Other Name: Converter Assembly, 3Way Catalytic (W/ Exhaust Manifold P; Catalytic Converter, Converter & Pipe
- Replaced by: 19418926
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2009-2013 GMC Sierra | CREW CAB 1/2 TON, EXTENDED CAB 5'8" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON, EXTENDED CAB 8' BOX 1/2 TON, REGULAR CAB 6'6" BOX 1/2 TON, REGULAR CAB 8' BOX 1/2 TON | 6 Cyl 4.3L, 8 Cyl 4.8L, 8 Cyl 4.8L Flex, 8 Cyl 5.3L, 8 Cyl 5.3L Flex, 8 Cyl 6.0L, 8 Cyl 6.0L Flex
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GMC Sierra CONVERTER ASM,3WAY CTLTC(W/EXH PIPE)
Part Number: 19420277
$2042.61 MSRP: $2882.96
You Save: $840.35 (30%)
ADD TO CART
Product Specifications
- Other Name: Catalytic Converter, Converter & Pipe
- Replaces: 23268768, 25811714, 84053222, 84053221
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2012-2019 GMC Sierra | 1 TON CREW CAB, 2500 CREW CAB STANDARD BOX, 2500 REGULAR CAB, 3500 CREW CAB LONG BOX, 3500 CREW CAB ONLY, 3500 CREW CAB STANDARD BOX, 3500 DOUBLE CAB LONG BOX, 3500 REGULAR CAB, CREW CAB 1 TON, CREW CAB 1 TON 119.0, CREW CAB 2500 LONG BOX, CREW CAB 6'6" BOX 3/4 TON, CREW CAB 8' BOX 3/4 TON, DOUBLE CAB 2500 LONG BOX, DOUBLE CAB 2500 STANDARD BOX, EXTENDED CAB 1 TON, EXTENDED CAB 6'6" BOX 3/4 TON, EXTENDED CAB 8' BOX 3/4 TON, REGULAR CAB 1 TON, REGULAR CAB 3/4 TON | 8 Cyl 6.0L, 8 Cyl 6.0L Flex
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GMC Sierra CONVERTER ASM,3WAY CTLTC(W/EXH PIPE)
Part Number: 19420265
$2022.57 MSRP: $3037.97
You Save: $1015.40 (34%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Catalytic Converter, Converter & Pipe
- Replaces: 23111625, 84362281
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2015-2018 GMC Sierra | 1500 CREW CAB, 1500 CREW CAB STANDARD BOX, 1500 DOUBLE CAB STANDARD BOX, 1500 REGULAR CAB LONG BOX, 1500 REGULAR CAB STANDARD BOX, CREW CAB 1/2 TON | 8 Cyl 6.2L
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GMC Sierra CONVERTER ASM,3WAY CTLTC(W/EXH PIPE)
Part Number: 19420284
$2518.55 MSRP: $3786.05
You Save: $1267.50 (34%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Catalytic Converter, Converter & Pipe
- Replaces: 22948166
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2014-2016 GMC Sierra | 1500 CREW CAB, 1500 CREW CAB STANDARD BOX, 1500 DOUBLE CAB STANDARD BOX, 1500 REGULAR CAB LONG BOX, 1500 REGULAR CAB STANDARD BOX, CREW CAB 1/2 TON | 8 Cyl 6.2L
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GMC Sierra CONVERTER ASM,3WAY CTLTC (W/EXH MANIF PIPE)"KIT"
Part Number: 19418932
$2255.33 MSRP: $3389.03
You Save: $1133.70 (34%)
Ships in 1-3 Business Days
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Product Specifications
- Other Name: Catalytic Converter, Converter & Pipe
- Replaces: 25824121
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2007-2008 GMC Sierra | CREW CAB 1/2 TON, EXTENDED CAB 5'8" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON, EXTENDED CAB 8' BOX 1/2 TON, REGULAR CAB 6'6" BOX 1/2 TON, REGULAR CAB 8' BOX 1/2 TON | 6 Cyl 4.3L, 8 Cyl 4.8L, 8 Cyl 5.3L, 8 Cyl 5.3L Flex, 8 Cyl 6.0L
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GMC Sierra CONVERTER ASM,3WAY CTLTC (W/EXH MANIF PIPE)"KIT"
Part Number: 19418941
$2125.30 MSRP: $3192.92
You Save: $1067.62 (34%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Catalytic Converter, Converter & Pipe
- Replaces: 20854454, 15905948
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2009-2013 GMC Sierra | CREW CAB 1/2 TON, EXTENDED CAB 5'8" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON, EXTENDED CAB 8' BOX 1/2 TON, REGULAR CAB 6'6" BOX 1/2 TON, REGULAR CAB 8' BOX 1/2 TON | 8 Cyl 4.8L, 8 Cyl 4.8L Flex, 8 Cyl 5.3L, 8 Cyl 5.3L Flex, 8 Cyl 6.0L, 8 Cyl 6.0L Flex
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GMC Sierra 3Way Catalytic Convertor Assembly (W/ Exhaust Manifold P
Part Number: 22940415
$2490.54 MSRP: $4366.67
You Save: $1876.13 (43%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Converter Assembly, 3Way Catalytic (W/ Exhaust Manifold P; Catalytic Converter, Converter & Pipe
- Replaces: 15905949
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2011-2013 GMC Sierra | CREW CAB 1/2 TON, EXTENDED CAB 5'8" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON, EXTENDED CAB 8' BOX 1/2 TON | 8 Cyl 6.2L Flex
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GMC Sierra 3Way Catalytic Convertor Assembly (W/ Exhaust Manifold P
Part Number: 22751290
$1350.86 MSRP: $2024.83
You Save: $673.97 (34%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Converter Assembly, 3Way Catalytic (W/ Exhaust Manifold P; Catalytic Converter
- Replaced by: 19418930
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2011-2015 GMC Sierra | 2500 REGULAR CAB, 3500 CREW CAB LONG BOX, 3500 CREW CAB ONLY, 3500 DOUBLE CAB LONG BOX, 3500 REGULAR CAB, CREW CAB 1 TON, CREW CAB 1 TON 137.0, CREW CAB 2500 LONG BOX, CREW CAB 8' BOX 3/4 TON, DOUBLE CAB 2500 LONG BOX, EXTENDED CAB 1 TON, EXTENDED CAB 8' BOX 3/4 TON, EXTENDED CREW CAB 1 TON 161.5, REGULAR CAB 1 TON, REGULAR CAB 3/4 TON, REGULAR CAB CHASSIS 1 TON 137.0, REGULAR CAB CHASSIS 1 TON 161.5 | 8 Cyl 6.0L Flex
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GMC Sierra CONVERTER ASM,3WAY CTLTC (W/EXH MANIF PIPE) "KIT"
Part Number: 19419599
$1741.19 MSRP: $2613.56
You Save: $872.37 (34%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Catalytic Converter, Converter & Pipe
- Replaces: 15896591
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2011-2013 GMC Sierra | CREW CAB 1/2 TON, EXTENDED CAB 5'8" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON, EXTENDED CAB 8' BOX 1/2 TON | 8 Cyl 6.2L Flex
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GMC Sierra 3-Way Catalytic Convertor Assembly (W/ Exhaust Manifold Pipe)
Part Number: 19208464
$992.35 MSRP: $1484.08
You Save: $491.73 (34%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Converter Asm,3Way Catalytic (W/ Exhaust Manifold Pipe); Catalytic Converter, Converter & Pipe
- Replaced by: 19420098
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2006-2007 GMC Sierra | 1500 CREW CAB STANDARD BOX, 1500 EXTENDED CAB LONG BOX, 1500 EXTENDED CAB SHORT BOX, 1500 EXTENDED CAB STANDARD BOX, 1500 REGULAR CAB LONG BOX, 1500 REGULAR CAB STANDARD BOX, CLASSIC 1500 CREW CAB STANDARD BOX, CLASSIC 1500 EXTENDED CAB LONG BOX, CLASSIC 1500 EXTENDED CAB SHORT BOX, CLASSIC 1500 EXTENDED CAB STANDARD BOX, CLASSIC 1500 REGULAR CAB LONG BOX, CLASSIC 1500 REGULAR CAB STANDARD BOX | 6 Cyl 4.3L, 8 Cyl 4.8L, 8 Cyl 5.3L, 8 Cyl 5.3L Flex
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GMC Sierra 3Way Catalytic Convertor Assembly (W/ Exhaust Manifold P
Part Number: 10395213
$946.55 MSRP: $1415.00
You Save: $468.45 (34%)
Ships in 1-3 Business Days
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Product Specifications
- Other Name: Converter Assembly, 3Way Catalytic (W/ Exhaust Manifold P; Catalytic Converter, Converter & Pipe, Front Pipe
- Replaced by: 19420124
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2001-2007 GMC Sierra | 1500 CREW CAB STANDARD BOX, 1500 EXTENDED CAB STANDARD BOX, CLASSIC 1500 CREW CAB STANDARD BOX, CLASSIC 1500 EXTENDED CAB STANDARD BOX | 8 Cyl 6.0L
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GMC Sierra 3Way Catalytic Convertor Assembly (W/ Exhaust Manifold P
Part Number: 10395214
$1230.70 MSRP: $1843.58
You Save: $612.88 (34%)
Ships in 1-3 Business Days
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Product Specifications
- Other Name: Converter Assembly, 3Way Catalytic (W/ Exhaust Manifold P; Catalytic Converter, Converter & Pipe, Front Pipe
- Replaced by: 19420109
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2001-2007 GMC Sierra | 1500 CREW CAB STANDARD BOX, 1500 EXTENDED CAB STANDARD BOX, CLASSIC 1500 CREW CAB STANDARD BOX, CLASSIC 1500 EXTENDED CAB STANDARD BOX | 8 Cyl 6.0L
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GMC Sierra 3Way Catalytic Convertor Assembly (W/Exhaust Pipe)
Part Number: 84655074
$1320.74 MSRP: $1979.40
You Save: $658.66 (34%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Converter Assembly, 3Way Ctltc(W/Exh Pipe); Catalytic Converter
- Replaced by: 86781749
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2019-2021 GMC Sierra | CREW CAB 5'8" 1/2 TON, CREW CAB 5'8" BOX 1/2 TON, CREW CAB 6'6" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON, EXTENDED CAB 8' BOX 1/2 TON, REGULAR CAB 6'6" BOX 1/2 TON, REGULAR CAB 8' BOX 1/2 TON | 6 Cyl 4.3L, 8 Cyl 5.3L
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GMC Sierra Converter Assembly, 3Way Ctltc(W/Exh Pipe)
Part Number: 84655075
$2081.78 MSRP: $3127.28
You Save: $1045.50 (34%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Catalytic Converter, Converter & Pipe
- Replaces: 84520355, 84557806
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2019-2021 GMC Sierra | CREW CAB 5'8" BOX 1/2 TON, CREW CAB 6'6" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON | 8 Cyl 6.2L
View related parts
GMC Sierra CONVERTER ASM,3WAY CTLTC (W/EXH MANIF PIPE)"KIT"
Part Number: 19418958
$2145.07 MSRP: $3416.66
You Save: $1271.59 (38%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Catalytic Converter, Converter & Pipe
- Replaces: 25904626, 20854457, 25904629
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2007-2010 GMC Sierra | CREW CAB 1/2 TON, EXTENDED CAB 5'8" BOX 1/2 TON, EXTENDED CAB 6'6" BOX 1/2 TON, EXTENDED CAB 8' BOX 1/2 TON | 8 Cyl 6.2L, 8 Cyl 6.2L Flex
View related parts
GMC Sierra 3Way Catalytic Convertor Assembly (W/Exhaust Pipe)
Part Number: 84653314
$1952.10 MSRP: $2931.67
You Save: $979.57 (34%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Converter Assembly, 3Way Ctltc(W/Exh Pipe); Catalytic Converter, Converter & Pipe
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2020-2021 GMC Sierra | CREW CAB 1 TON CHASSIS 137.0, CREW CAB 6'6" BOX 1 TON, CREW CAB 6'6" BOX 3/4 TON, CREW CAB 8' BOX 1 TON, CREW CAB 8' BOX 3/4 TON, EXTENDED CAB 6'6" BOX 3/4 TON, EXTENDED CAB 8' BOX 1 TON, EXTENDED CAB 8' BOX 3/4 TON, EXTENDED CREW CAB 1 TON CHASSIS 161.5, REGULAR CAB 1 TON CHASSIS 137.0, REGULAR CAB 1 TON CHASSIS 161.5, REGULAR CAB 8' BOX 1 TON, REGULAR CAB 8' BOX 3/4 TON | 8 Cyl 6.6L
View related parts
GMC Sierra NOX Catalytic Converter Assembly (W/ Exh Pipe)
Part Number: 84341182
$510.55 MSRP: $757.39
You Save: $246.84 (33%)
ADD TO CART
Product Specifications
- Other Name: Converter Assembly, Nox Ctltc (W/ Exh Pipe); Catalytic Converter, Converter & Pipe
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2020-2021 GMC Sierra | CREW CAB 1 TON CHASSIS 137.0, CREW CAB 6'6" BOX 1 TON, CREW CAB 6'6" BOX 3/4 TON, CREW CAB 8' BOX 1 TON, CREW CAB 8' BOX 3/4 TON, EXTENDED CAB 6'6" BOX 3/4 TON, EXTENDED CAB 8' BOX 1 TON, EXTENDED CAB 8' BOX 3/4 TON, EXTENDED CREW CAB 1 TON CHASSIS 161.5, REGULAR CAB 1 TON CHASSIS 137.0, REGULAR CAB 1 TON CHASSIS 161.5, REGULAR CAB 8' BOX 1 TON, REGULAR CAB 8' BOX 3/4 TON | 8 Cyl 6.6L Diesel
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GMC Sierra Converter Assembly, Oxidn Ctltc
Part Number: 12705096
$699.03 MSRP: $1041.67
You Save: $342.64 (33%)
Ships in 1-3 Business Days
ADD TO CART
Product Specifications
- Other Name: Catalytic Converter, Converter
- Replaces: 19420224, 12680277
- Warranty: This genuine part is guaranteed by GM's factory warranty.
Fits the following Vehicles:
- 2017-2021 GMC Sierra | 2500 CREW CAB STANDARD BOX, 2500 REGULAR CAB, 2500 REGULAR CAB STANDARD BOX, 3500 CREW CAB LONG BOX, 3500 CREW CAB ONLY, 3500 CREW CAB STANDARD BOX, 3500 DOUBLE CAB LONG BOX, 3500 REGULAR CAB, CREW CAB 1 TON CHASSIS 137.0, CREW CAB 2500 LONG BOX, CREW CAB 6'6" BOX 1 TON, CREW CAB 6'6" BOX 3/4 TON, CREW CAB 8' BOX 1 TON, CREW CAB 8' BOX 3/4 TON, DOUBLE CAB 2500 LONG BOX, DOUBLE CAB 2500 STANDARD BOX, EXTENDED CAB 6'6" BOX 3/4 TON, EXTENDED CAB 8' BOX 1 TON, EXTENDED CAB 8' BOX 3/4 TON, EXTENDED CREW CAB 1 TON CHASSIS 161.5, REGULAR CAB 1 TON CHASSIS 137.0, REGULAR CAB 1 TON CHASSIS 161.5, REGULAR CAB 8' BOX 1 TON, REGULAR CAB 8' BOX 3/4 TON | 8 Cyl 6.6L Diesel

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GMC Sierra Catalytic Converter Parts Questions & Experts Answers

3Way Catalytic Convertor Assembly (W/ Exhaust Manifold P
25782037
Q: What is a catalytic converter and how do you diagnose and repair it?
A: A catalytic converter is an emission control device that reduces certain pollutants. There are two types of converters: an oxidation catalyst that reduces hydrocarbons and carbon monoxide, and a reduction catalyst that reduces oxides of nitrogen. Vehicles are equipped with two three-way catalysts that can reduce all three pollutants. Whenever you raise the vehicle to service underbody components, inspect the converter for leaks, corrosion, dents, and other damage. The easiest way to check for a restricted converter is to use a vacuum gauge to diagnose the effect of a blocked exhaust on the intake vacuum. To remove the converter, raise the vehicle and place it securely on jack stands, disconnect the electrical connectors for the upstream and downstream Oxygen Sensors, remove all four sensors, remove the nuts at each of the upper flanges that secure the front exhaust pipe assembly to the exhaust manifold flanges, remove the nuts that secure the rear flange of the front exhaust pipe assembly to the rest of the exhaust system, and remove the front exhaust pipe assembly. To install the converter, coat the threads of the nuts and bolts with an anti-seize compound to facilitate future removal and tighten the nuts that secure the front exhaust pipe assembly to the exhaust manifold and to the rest of the exhaust system securely.