P0172 on Pontiac
System Too Rich (Bank 1)
P0172 on Pontiac vehicles indicates system too rich (bank 1). Au7o has documented this code across 1 Pontiac model — most commonly on Bonneville. P0172 means the engine computer has determined the air/fuel mixture on bank 1 is too rich — there is too much fuel relative to air. The PCM watches the oxygen sensors and fuel trims; when it must repeatedly cut back fuel to compensate for an over-rich condition and hits its correction limit, it sets this code. Bank 1 is the side of the engine containing cylinder number one. You may notice poor fuel economy, rough idle, a sulfur/rotten-egg smell, black exhaust smoke, or fouled spark plugs.
Common Causes of P0172
- •Dirty or faulty mass airflow (MAF) sensor
- •Leaking or stuck fuel injector
- •High fuel pressure (faulty regulator)
- •Faulty oxygen sensor giving skewed readings
- •Clogged or dirty air filter
- •Leaking evaporative purge valve adding fuel vapor
- •Engine coolant temperature sensor reading too cold
- •Worn spark plugs causing inefficient combustion
P0172 on Pontiac by Model
Pontiac Bonneville(1 issue)
- 3800 V6 (L36) Fuel Pressure Regulator Leak Can Cause Backfire and Fire (NHTSA Recall 04V090000)1998-2000
This safety recall applies to 1998-2000 Bonnevilles fitted with the naturally aspirated 3800 V6 (L36) and one of the suspect Delphi fuel pressure regulators. Those regulators fail at a far higher rate than normal, and the leak path matters: fuel escapes into the intake manifold by way of a vacuum line. The hazard shows up during a no-start. Crank a Bonneville that won't fire, and the accumulated fuel plus a mistimed spark can set off a backfire strong enough to rupture the intake manifold. NHTSA warns that such a rupture can shift a fuel line and pull an injector out of place — the result is a fuel leak and possible fire. Owners were notified in two phased mailings beginning June 30, 2004 and September 30, 2004. In total the campaign spanned 910,873 vehicles across every model it covered.
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View P0172 across all makes →Frequently Asked Questions
What does P0172 mean on Pontiac?▼
P0172 stands for "System Too Rich (Bank 1)." P0172 means the engine computer has determined the air/fuel mixture on bank 1 is too rich — there is too much fuel relative to air. The PCM watches the oxygen sensors and fuel trims; when it must repeatedly cut back fuel to compensate for an over-rich condition and hits its correction limit, it sets this code. Bank 1 is the side of the engine containing cylinder number one. You may notice poor fuel economy, rough idle, a sulfur/rotten-egg smell, black exhaust smoke, or fouled spark plugs. On Pontiac specifically, this code is documented across 1 model.
What causes P0172 on Pontiac vehicles?▼
Common causes on Pontiac: Dirty or faulty mass airflow (MAF) sensor, Leaking or stuck fuel injector, High fuel pressure (faulty regulator), Faulty oxygen sensor giving skewed readings, Clogged or dirty air filter. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0172 on a Pontiac?▼
Repair costs vary widely depending on the root cause and specific Pontiac model.
Which Pontiac models have P0172 documented?▼
Au7o has documented P0172 on 1 Pontiac model: Bonneville.