Nissan P0171

System lean on Nissan — Qashqai/Juke 1.6 HR16 and 1.2 DIG-T MAF and intake leaks.

Nissan P0171 — System lean on Nissan — Qashqai/Juke 1.6 HR16 and 1.2 DIG-T MAF and intake leaks. Typical UK independent garage cost: £25–£450.

What actually causes P0171 on a Nissan

Nissan HR16 P0171 is usually MAF contamination after 60k — these MAFs are unusually sensitive to oil mist from worn PCV systems. On HR12 DIG-T turbo, intake hose splits and PCV diaphragm failures dominate. The HR12 is a complicated little engine and P0171 with limp mode usually means a meaningful leak, not just a dirty MAF.

Nissan engines that log P0171

• HR16DE 1.6 (Qashqai/Juke)
• HR12DDT 1.2 DIG-T (Juke/Pulsar)
• MR20DE 2.0

How we diagnose P0171 on a Nissan

1. Log MAF and fuel trims with Nissan Consult or Autel
2. Smoke-test full intake from MAF to inlet manifold
3. Inspect HR12 charge pipes and PCV for splits
4. Clean MAF and re-test
5. Check intake manifold gasket integrity on HR16 over 100k

The common misdiagnosis to avoid

HR12 DIG-T P0171 with limp mode — smoke-test before MAF cleaning. These turbos crack intake hoses regularly.

Nissan P0171 repair cost in the UK

Expect £25–£450 including parts and labour at an independent garage. Main-dealer quotes on Nissan are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.

Bob's workshop tip

Worn PCV on HR16 oil-mists the MAF and you'll be cleaning it every 6 months — fix the PCV root cause and the MAF stays clean.

Codes usually seen alongside P0171 on Nissan

• P0174
• P0507
• P0300

Symptoms drivers report with P0171

• Hesitation or 'flat spot' pulling away from junctions and roundabouts when engine is warm
• Rough or lumpy idle, worse when air-con clicks in (extra load exposes the lean condition)
• Occasional cough or backfire through the intake when accelerating hard from low RPM
• MPG dropping 3–8 mpg over the last month with no change in driving style
• Faint hissing under the bonnet at idle (vacuum leak from cracked manifold or split hose)
• Paired codes: P0174 (bank 2 lean, V6/V8 only), P0507 (idle too high), P2187 (idle lean), P0300-series misfires

Repairs that clear P0171

• Smoke-test for vacuum leaks
• Clean MAF sensor with proper cleaner
• Test fuel pressure
• Replace fuel filter
• Replace failed sensor

For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0171 guide.