Product images and videos are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Air and Fuel› Air Cleaners, Filters, Intakes and Components

CTS Turbo

85mm MAF Housing

Name: 85mm MAF Housing
Brand: CTS Turbo
SKU: CTS-HW-040

$499.99

SKU: CTS-HW-040

Free Shipping over $200

$100 Minimum Order

Non-Returnable Item

DIY PRO SHOP

Easy — 1–2 hours

Overview

The CTS Turbo MAF Housing is an 85mm diameter housing designed for modified B5 Audi S4, RS4, and C5 Audi A6/Allroad 2.7T vehicles. It is intended for use with RS4 or larger turbochargers, upgraded software, and fuel injectors. This housing comes in a raw aluminum finish and includes mounting bolts. It is specifically for Hitachi MAF sensors only.

Show original supplier description

The CTS Turbo B5 S4 85mm MAF Housing is engineered for enhanced airflow in modified B5 Audi S4, RS4, and C5 Audi A6/Allroad 2.7T vehicles. This housing is specifically designed for vehicles equipped with RS4 or larger turbochargers, necessitating upgraded software and fuel injectors for optimal performance. Constructed from durable aluminum with a raw finish, this MAF housing features an 85mm inside diameter to accommodate increased airflow demands. It is designed exclusively for use with Hitachi MAF sensors, ensuring compatibility with specific sensor types. The housing includes all necessary mounting bolts for installation and can be paired with an optional stock airbox adapter (CTS-HW-164). Installation is recommended for B5 S4 models with a Stage 3 upgrade, though users are advised to confirm the housing size with their software tuner prior to ordering. The MAF housing is designed to be a direct fit for the Audi S4 B5 (1999-2002) with the 2.7T engine.

Vehicle Symptoms

Engine stumbles or hesitates under full boost
Lack of power after turbo upgrade
Check Engine Light on with MAF-related codes
Poor fuel economy after engine modifications
Rough idle or surging at idle

Diagnostic Codes

P0101 – Mass or Volume Air Flow Ckt Range/Perf
P0102 – Mass or Volume Air Flow Ckt Low In
P0103 – Mass or Volume Air Flow Ckt High In
P0100 – Mass or Volume Air Flow Ckt
P0171 – FT Malf (B1)
P0174 – FT Malf (B2)

Relevant Conversations

B5 S4 85mm MAF housing upgrade for RS4 turbos
CTS Turbo 85mm MAF housing review
P0101 code after installing RS4 turbos on B5 S4
85mm vs 3 inch MAF housing for 2.7T
B5 S4 fuel trims lean after MAF upgrade
CTS-HW-040 installation guide
Hitachi MAF sensor compatible with 85mm housing
B5 S4 MAF housing for 550cc injectors
Audi 2.7T 85mm MAF housing tuning
B5 S4 rough idle after MAF housing swap

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

Fitment Guaranteed

Don’t gamble
on fit.

Log your build in the MOTORMIA app and we’ll guarantee this part fits your exact setup — or your money back, return shipping covered.

Available on iOS & Android

Specifications

Brand	CTS Turbo
Part Number	CTS-HW-040
Category	Air and Fuel

5,000+ Trusted brands

1M+ Enthusiasts

5M+ Parts sold

(760) 282-4645 hello@motormia.co

Buy with Confidence

Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

View Full Return Policy

Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

View Full Shipping Policy