P0170

Fuel Trim Bank 1

Fuel & air metering Generic OBD-II High

What it means

P0170 means the engine computer has had to correct fueling on bank 1 by more than it allows — the mixture is running too rich or too lean and the computer can't bring it back into range. It's usually a symptom of another problem: a vacuum leak, a dirty MAF, a weak fuel supply, or a failing oxygen sensor. It often shows up alongside a lean or rich code that points to the exact cause.

High

Can I keep driving? Usually drivable, but the engine may run rough or use extra fuel; fix it before a persistent rich or lean condition fouls plugs or the converter.

Real-world scan data

Seen in

1,331

scans in the past year

Found in

0.2%

of scans

0.4%

of scans that found faults

Appears alongside · share of P0170 scans

P0420in 29.8% of scans

P2119in 26.7% of scans

P0380in 25.5% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Poor fuel economy
Rough idle or stalling
Hesitation or reduced power
Hard starting in some cases

Common causes

Most likely first

Vacuum or intake leaks (lean condition)Likely
Dirty or faulty MAF sensorCommon
Faulty oxygen sensorCommon
Fuel-delivery problems — clogged injectors or filter, weak pumpLess often
Failing fuel pressure regulatorLess often
Failed ECM (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and note the fuel-trim values and any partner codes (e.g. P0171 or P0172).
Check for vacuum and intake leaks.
Inspect the MAF sensor and clean it if dirty.
Verify fuel pressure and check the oxygen sensor's switching.
Inspect the injectors and fuel filter; suspect the ECM last.

FAQ

Quick answers

Is it safe to drive with P0170?+

Short trips are usually okay, but a large mixture error can cause stalling, misfires, and eventually converter damage. Get it diagnosed before it worsens.

Can I just clear P0170?+

It will return once the computer relearns fuel trims, because the underlying rich or lean condition is still there — usually a leak, a MAF, or a fuel-delivery issue.

Read & clear P0170 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX