P0170

Code

GWM P — Powertrain

- The composition of the mixture is incorrectly balanced (bank 1)

Brand: GWM

Type: P — Powertrain

Views: UK: 5 EN: 4 RU: 8

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Page language: EN

Causes

Faulty or slow responding upstream oxygen (O2) sensor on bank 1
Mass airflow (MAF) or manifold absolute pressure (MAP) sensor fault or contamination
Vacuum or intake manifold leak upstream of the intake runners (affecting bank 1)
Fuel delivery problem (low rail pressure, weak pump, clogged filter, leaking/blocked injector)
Exhaust leak upstream of the O2 sensor
Wiring or connector faults to sensors (O2, MAF, MAP, fuel pressure sensor) or PCM

Symptoms

Check Engine (MIL) illuminated
Poor fuel economy
Rough idle or hesitation under acceleration
Hard starting or stalling in some cases
Possible increased exhaust emissions or abnormal exhaust odor

What to check

Read and record all stored and pending DTCs and freeze-frame data
Monitor live data: short-term fuel trim (STFT) and long-term fuel trim (LTFT) for bank 1, O2 sensor voltages, MAF/MAP readings
Compare measured sensor values to manufacturer specifications
Perform visual inspection for vacuum leaks, cracked hoses, intake gasket leaks, or disconnected vacuum lines
Inspect wiring and connectors for bank 1 O2/MAF/MAP/fuel sensors for corrosion, damage, or poor grounds
Measure fuel rail pressure at key-on and while cranking/running

Signal parameters

Short-term/long-term fuel trim: typically within ±10% at idle; excursions beyond ±25% indicate severe lean/rich or sensor/trim malfunction
Upstream narrowband O2 sensor: typically toggles ~0.1–0.9 V; slow or fixed voltage indicates fault
Wideband O2 sensor: voltage/current or AFR output should track commanded AFRs (compare to spec)
MAF sensor: grams/sec or Hz/frequency values vary by engine; idle values should match factory spec (compare scanner live data)
Fuel rail pressure: gasoline systems commonly ~30–60 psi (check vehicle spec); significant drop under load indicates pump/regulator issue

Diagnostic algorithm

Retrieve all DTCs and freeze-frame data. Note conditions when code set (engine temp, load, rpm).
Clear codes and road-test while monitoring STFT/LTFT, O2 sensor voltage, and MAF/MAP to see when/if P0170 returns.
Inspect intake tract for obvious vacuum leaks, cracked hoses, loose clamps, intake manifold bolts, and PCV connections. Repair as needed.
Verify MAF sensor condition: visually inspect and, if dirty, clean with proper MAF cleaner. Re-test. Compare MAF readings to known-good values or spec.
Check upstream O2 sensor operation: observe switching behavior (narrowband) or AFR tracking (wideband). Replace only if confirmed bad.
Measure fuel pressure/static and under load. Repair fuel pump, regulator, or filter if pressure is out of spec.
Perform wiring and connector checks for sensors and ground circuits on bank 1 — repair shorts/opens/corrosion.
Perform smoke test of intake and PCV system to find hidden leaks if fuel trim indicates a lean condition with no obvious leak.
If injectors are suspected, perform balance or flow testing and inspect for leaking injectors contributing to rich conditions.
After repairs or sensor replacements, clear codes and re-check for proper fuel trim behavior and confirm P0170 does not return.
Consider ECU/PCM update or replacement only after all sensors, wiring, and mechanical systems are verified good.

Likely causes

Upstream O2 sensor on bank 1 failing or slow to switch
MAF sensor contamination or incorrect MAF signal
Intake vacuum leak or cracked hose feeding bank 1
Low fuel pressure or weak injector(s) on bank 1
Damaged sensor wiring or poor connector ground to bank 1 sensors

Fault status

⚠️ Status

Malfunction indicator lamp (MIL) set — PCM detected inconsistent fuel trim control or invalid sensor feedback for bank 1. Investigation of sensors, fuel delivery, intake leaks, and wiring required.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-3.0 hours

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P0170 — - The composition of the mixture is incorrectly balanced (bank 1)