Mazda CX-5 Exhaust System: Specs, Fitment & Common Faults
A genuinely severe, real issue on diesel models: two independent mechanics described diesel fuel contaminating the oil as a known manufacturing fault, with Mazda quoting £9,000 for a replacement engine.
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OEM Part Number: confirm via VIN — Rear silencer (aftermarket) Bosal 171-045 / Walker 71393
| Rear silencer (back box) — aftermarket | Walker 71393 (820 mm); Walker 71394; Walker 21303 (790 mm); Bosal 171-045 / 154-923 / 171-055 (accessories needed); Ernst 311199, 310161; Vegaz FS-621, MZS-134, MZS-66; MTS 01.92260, 01.92280, 01.94640 |
|---|---|
| Centre / intermediate silencer — aftermarket | Walker 23109; Bosal 171-377; Vegaz MZS-16, MZS-156 (manual), MZS-169, MZS-198, MZS-199; Hella 8LC 366 024-061 / -071; Izawit 17.079 |
| Front pipe / catalytic converter (DPF on diesels) — aftermarket | Bosal 090-003 (Euro 4); Walker 28532, 28109, 20758; Quinton Hazell QCAT90454H; NAP CAK10405 (ZL05/ZL06), CAK10261 (Euro 4); JMJ 1091529; Ernst 313476 (repair pipe) |
| Genuine (OE) numbers quoted | None quoted in catalogue listings — order genuine parts against your VIN |
| Fitment notes | engines petrol 2.0/2.5, diesel 2.2 D (incl. AWD); not engine-specific; NAP CAK10408 flagged 1994-2001, ignore. |
A Genuinely Severe, Real Issue Worth Understanding on Diesel Models — Mazda CX-5 Exhaust System
This is genuinely important to understand on the 2.2 diesel engine specifically: unburnt diesel fuel injected during a DPF regeneration cycle can, in some documented cases, work its way past the piston rings and into the engine oil rather than being fully burned off, progressively diluting and contaminating it. One documented case saw two independent mechanics both describe this as a known manufacturing fault affecting these diesel engines, with the contaminated oil eventually causing the engine to knock and fail entirely — Mazda themselves quoted around £9,000 for a full replacement engine in this case. Staying on top of oil changes at or before the recommended interval, and being aware that a diesel smell on the dipstick or a rising oil level between changes can be an early warning sign of this specific issue, is genuinely worth taking seriously rather than dismissing as normal.
It's also worth knowing about a genuinely specific, distinctive symptom combination worth recognising: a warning specifically referencing "SCBS forward malfunction" appearing during deceleration or engine braking, alongside a general engine warning light, has been documented as pointing toward significant carbon buildup in the intake manifold requiring a full decoke, along with a compromised EGR cooler — worth mentioning this specific symptom pattern to a specialist if you're getting an unusual combination of warnings during deceleration specifically.
Mazda CX-5 Exhaust System: The Part That Announces Its Own Problems
Where a lot of Mazda CX-5 parts fail silently until you spot something visually wrong, this one tends to make noise first — a rattle, a drone, an audible change that wasn't there recently. That's a useful early-warning system if you're paying attention.
Mazda CX-5 Exhaust System: Watch: Replacing It
2015 CX-5 (KE) exhaust kit install
Mazda CX-5 Exhaust System: What It Does
Away from the engine, through the silencer, and often through a catalytic converter and particulate filter before reaching the tailpipe — that's the Mazda CX-5's exhaust job in three steps. Petrol and diesel versions frequently need different systems entirely, since their emissions treatment isn't the same.
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Mazda CX-5 Exhaust System: Warning Signs, DIY Difficulty & Aftermarket Advice
These are the same regardless of make or model — see our full Exhaust System Guide for warning signs and fault codes to watch for, confirming fitment against your VIN, and which aftermarket brands are worth trusting.
More Mazda Exhaust System
The same part, covered across other Mazda models.