Pontiac Sunfire Check Engine Light and Stalling in Kirkland, WA: P0440, a Smoke Test and a Large Vacuum Leak

A 2001 Pontiac Sunfire SE came into our Kirkland shop at 92,265 miles with two complaints: the check engine light was on, and the car was stalling as it came to a stop. It left on October 15 with a new purge valve, a new vent solenoid, a new gas cap and a new throttle body seal, and it passed a road test with no stalling.

What the scan tool found

We connected our diagnostic equipment and ran a full fault survey. The engine computer had one code stored:

• P0440: Evaporative emission (EVAP) system leak

The smoke test found two leaks

Our technician smoke tested both the EVAP system and the intake tract. The smoke test found two leaks:

1. A large vacuum leak at the purge valve.

2. A leak at the coupler between the intake and the throttle body.

The work performed

Diagnosis and EVAP / intake leak repair: $900–$1,200. Full fault survey, smoke test of the EVAP system and the intake tract, then:

• Removed the throttle body and the old purge valve, and installed a new genuine GM purge valve

• Installed a new genuine GM intake seal between the throttle body and the intake pipe

• Installed a new vapor canister vent solenoid

• Installed a new genuine GM gas cap with tether strap

Then the checks: codes cleared, the intake rechecked for leaks (none found), and a road test. From the record: no stalling, no faults returned, and the EVAP system passed its system test. Recorded labor on this line: 3 hours. Engine diagnostics and fuel and emissions system repair.

Loose rear view mirror: no charge. The mirror’s plastic mount was cracked. The replacement part is no longer available, so we snugged it up as well as it would go.

What the inspection flagged, but we didn’t fix

Our multi-point inspection on this Sunfire turned up several things worth watching. None of them were part of this visit.

• The battery failed a load test. It carries a 2022 date code, and the tester called for replacement at 67% of its rated cold cranking amps.

• The front control arm bushings are starting to crack and separate.

• The A/C condenser is leaking at its bottom corner.

• A slight leak is developing at the front crankshaft seal.

• The power steering rack boot is seeping, and the transmission pan seal is damp. We’ll check both again at the next visit.

The battery load test: 12.58 volts at rest, but only 67% of its rated cranking amps under load. The tester’s verdict was replace.

Front control arm bushings starting to crack and separate. Flagged for a future visit.

The A/C condenser, wet and grimy along its bottom corner where it’s leaking.

The brakes (5 to 6 mm front, 4 mm rear shoes) and tires (8/32 and 9/32 inch) were in good shape.

What it cost

The visit landed in the $900–$1,200 range, completed October 2026. Labor was the larger share. On parts, the genuine GM purge valve was the biggest item, followed by the intake seal, gas cap and vent solenoid.

That range reflects a completed historical project, not a current quote.

Questions about this job

Did the stalling stop?

Yes. After the purge valve and throttle body seal were replaced, the road test found no stalling, no faults returned, and the EVAP system passed its system test.

What parts were replaced?

A genuine GM purge valve, a genuine GM intake seal at the throttle body, a vapor canister vent solenoid and a genuine GM gas cap, all on this visit.

Why a smoke test?

The smoke test found two leaks, and one of them was in the intake at the throttle body coupler, not in the EVAP system the code named.

What about the battery?

It failed its load test on this visit and wasn’t replaced. More on our battery testing service.

Do you work on older GM cars?

Yes. This Sunfire is 25 years old and got genuine GM parts where they were available. More on our Chevrolet and GM repair in Kirkland.

Prepared from our job records for this vehicle: the repair order and technician notes, the diagnostic scan, the smoke test, the multi-point inspection with photos, the parts list and the final invoice. The cover photo is a stock image; the photos in the post are from this car.