C0040 on Pontiac: How to Diagnose & Fix
Right Front Wheel Speed Sensor Circuit
1 Pontiac model · 1 documented issue · $250-$500 repair
C0040 on Pontiac by model: symptoms, diagnosis and fix
The sealed front hub bearing assemblies, which also house the ABS wheel-speed sensors, wear out prematurely and repeatedly on this generation — owners report replacing the same corner two or three times within a few years. As the bearing develops play, the integrated sensor signal drops out and the ABS, TRAC OFF, and SERVICE VEHICLE SOON lights come on, and a badly worn bearing left unaddressed risks wheel looseness. Flexing front sensor harness wires breaking at the strut are a common secondary trigger for the same warning lights.
Common Symptoms
- Humming or growling that rises with road speed
- Noise changes pitch when steering left or right
- ABS, TRAC OFF, and Service Vehicle Soon lights on
- Vibration or looseness felt in the steering wheel
- Same bearing failing again within 1-3 years
How to Fix
Replace the complete hub/bearing assembly (the sensor is integral and not serviceable separately) with a quality unit, torqued to spec with a new axle nut. Inspect and repair the wheel-speed sensor harness where it flexes near the strut before condemning a second hub.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Timken 513137 front wheel-bearing and hub assembly
1999-2005 Pontiac Grand Am FWD, front left or right. Sold individually; identify axle-nut design and required new hardware before installation.
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Sources for this issue (4)
- 2003 Pontiac Grand Am Wheel Bearings Failure — CarComplaints (9 complaints, repeat failures, ABS/TRAC OFF lights)forum
- Pontiac Grand Am Wheel Bearing and Hub Assembly Guide (1999-2005) — Go-Partsarticle
- 2004 Pontiac Grand Am: SERVICE VEHICLE, ABS, TRAC OFF lights come on, no stored hard codes — 2CarPros (wheel speed sensor/wiring diagnosis)forum
- Pontiac Grand Am Service Engine Soon / ABS / Trac Off — Edmunds Car Forums (multi-page owner thread on hub sensor/wiring failures)forum
C0040 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does C0040 mean on a Pontiac?
C0040 stands for "Right Front Wheel Speed Sensor Circuit." This is a brake/ABS-system code. The right front wheel speed sensor measures how fast that wheel is rotating and feeds that data to the anti-lock brake, traction control, and stability control systems. C0040 means the ABS module found an electrical problem in the right front wheel speed sensor circuit — for example an open circuit, a short, or a signal that is missing or out of range. You'll normally see the ABS and traction/stability lights come on, and those systems may shut off temporarily while your regular brakes keep working. On Pontiac it is documented across 1 model: Grand Am.
What are the most common causes of C0040?
The most common causes of C0040 are: Failed right front wheel speed sensor, Damaged, corroded or unplugged sensor wiring/connector, Damaged or rust-clogged tone/reluctor ring, Excessive air gap between sensor and tone ring, Wheel bearing wear affecting an integrated sensor, Water intrusion or corrosion at the connector, Faulty ABS control module (less common). The specific cause varies by vehicle.
How much does it cost to fix C0040 on a Pontiac?
Published repair estimates on Pontiac range from $250 to $500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for C0040 on a different make?
View C0040 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.