Diagnostic Sheet
FROM: Maserati TSO
TO: Maserati Network

Rear Exhaust Silencer – Noise and Bypass Valve
Diagnostic Guide
DATE: April 9, 2026

This bulletin provides instructions for diagnosing and correcting issues with the rear exhaust
silencer. These issues may include exhaust noise or bypass valve problems (including DTC P1217
and P2D1100). A BOL may be required dependant on diagnostic outcome of the steps below.
Models Covered:
This bulletin applies to all model years of the following vehicles equipped with V6 and V8 engines:
•
•
•

Quattroporte (M156)
Ghibli (M157)
Levante (M161)

It also applies to all model years of the Grecale MHEV hybrid.

Choose the correct checklist based on the model and concern:
•
•
•

Checklist A: Noise – M15x/M161 (V6, V8)
Checklist B: Noise – Grecale MHEV
Checklist C: Bypass Valve Blockage & DTCs – Grecale MHEV

Important Note
If a BOL is opened, All required photos and information must be attached as well as all diagnostic
steps documented in the Blue On Line report. Maserati may modify or reject claims that are
incomplete or do not meet the criteria.
For help or clarification, contact Technical Service Operations.

© 2026 Maserati Americas.
Aftersales
www.maseratiusa.com

MAS005101

All rights reserved. Reproduction or translation in
whole or in part is not permitted without
authorization from the publisher. Printed in USA

Page 1 of 6

TECHNICAL SERVICE OPERATIONS

MAS005101 DS 26-06

TECHNICAL SERVICE OPERATIONS

Repair Procedure
Checklist A – Noise Concern (M15x–M161, V6 and V8)
1. Collect details from the customer:
o Does the noise occur with a hot or cold engine?
o Which driving mode (Sport, Normal, etc.)?
o Does the noise happen at idle or during acceleration?
2. Perform the following checks:
Use the diagram from the original document as reference.
o 3a: Check the tightening and condition of all anti-vibration pads (components 8, 9, 11, 12).
o 3b: Check the tightening of the exhaust collars at the indicated arrows.
o 3c: Check the tightening of the nuts on the central silencer support (component 17).

If the issue is fixed (BOL not necessary):
o

Use warranty code:
▪ Component Code: 1.81.001 – 1.81.002
▪ Tightening Check: 1.81.001.A (0.10 h)

Continued on next page

© 2026 Maserati Americas.
Aftersales
www.maseratiusa.com

MAS005101

All rights reserved. Reproduction or translation in
whole or in part is not permitted without
authorization from the publisher. Printed in USA

Page 2 of 6

4. If valves ARE working properly:
o Open a Blue On Line as “Support Request”.
o Attach pictures of valve behavior and identification numbers stamped on both silencers.

5. If valves do NOT work properly:
o Replace the rear silencer (or both silencers).
Warranty codes for this step:
Description

Code
1.81.001 – 1.81.002

Component Code
Check Valve Exhaust Noise with or without
replacing the rear silencers
M157

1.81.001.B (0,85 h)

M156

1.81.001.B (0,65 h)

M161

1.81.001.B (0,70 h)

© 2026 Maserati Americas.
Aftersales
www.maseratiusa.com

MAS005101

All rights reserved. Reproduction or translation in
whole or in part is not permitted without
authorization from the publisher. Printed in USA

Page 3 of 6

TECHNICAL SERVICE OPERATIONS

3. If the noise continues:
o Remove both rear silencers.
o Check if the bypass valves fully close in “Normal” mode. A valve that does not close can
cause rattling or vibration.
o Compare against the photo example below (poor closing of the valve); inspection must
be performed on both the silencers:

TECHNICAL SERVICE OPERATIONS

Checklist B – Noise Concern (Grecale MHEV)
1. Identify customer conditions:
o Hot or cold engine?
o Driving mode? (Sport, Normal, etc.)
o Idle or acceleration?
2. Check for ECM software updates using MD Evo.
o If an ECM update is available, install it and recheck the noise.
o Do NOT replace the exhaust system or remove the flap valve.
If resolved (BOL not necessary):
Warranty codes:
▪ Component Code: 1.90.001
▪ ECM SW Update: 1.90.001.9 (0.20 h)
3. If noise persists:
Perform these checks using the image provided:
o 3a: Check the tightening/condition of the rear anti-vibration pads (component 2).
o 3b: Check tightening of the exhaust collar at the indicated arrow.
o 3c: Check tightening/condition of the central silencer support pad (component 8).
o

IMPORTANT: Do NOT remove the by-pass valve actuator from its seat (see red circle in diagram).
If fixed (No BOL necessary):
o

Warranty codes:
▪ Component Code: 1.81.059
▪ Tightening Check: 1.81.059.B (0.10 h)

Continued on next page

© 2026 Maserati Americas.
Aftersales
www.maseratiusa.com

MAS005101

All rights reserved. Reproduction or translation in
whole or in part is not permitted without
authorization from the publisher. Printed in USA

Page 4 of 6

TECHNICAL SERVICE OPERATIONS

4. If noise continues:
o Select “GT” mode and start engine at idle.
o Disconnect the by-pass valve connector (valve should stay closed).
o Turn engine off.
o Disconnect rear silencer from center silencer.
o Inspect the valve using an endoscope.
o Compare images: correct vs incorrect valve mounting.
o Document with photos.

5. If valves are correct:
o Open a Blue On Line Support Request and attach photos, including silencer
identification stamps.

6. If valves are incorrectly installed:
o Replace the rear silencer.
Warranty code:
Description

Code

Component Code

1.81.059

Check Valve Exhaust Noise with or without

1.81.059.C (0,65 h)

replacing the rear silencer

© 2026 Maserati Americas.
Aftersales
www.maseratiusa.com

MAS005101

All rights reserved. Reproduction or translation in
whole or in part is not permitted without
authorization from the publisher. Printed in USA

Page 5 of 6

TECHNICAL SERVICE OPERATIONS

Checklist C – Bypass Valve Blockage + DTC P1217 and
P2D1100 (Grecale MHEV)
1. Customer Questionnaire:
o Does the customer use petrol and/or oil additives and if so, what type?

o

Does the customer refuel at the same service station?

2. Inspect for corrosion:
o Disconnect the rear silencer from the center silencer.
o Use an endoscope to inspect the bypass valve.
o Take photos, especially of any corrosion or oxidation.

3. If corrosion is present:
o Open Blue On Line Factory Information request and attach photos.
o Replace the rear silencer.
o Note: Corrosion cases are NOT covered under warranty.
4. If no corrosion:
o Open a Blue On Line Support Request.
o Attach photos of valve condition and stamped identification data.

Warranty code (only when corrosion is NOT present):
o
o

Component Code: 1.81.059
Corrosion Check / Replacement: 1.81.059.C (0.65 h)

© 2026 Maserati Americas.
Aftersales
www.maseratiusa.com

MAS005101

All rights reserved. Reproduction or translation in
whole or in part is not permitted without
authorization from the publisher. Printed in USA

Page 6 of 6