Fuel Temp Sensor #2 Short to Ground
The B1229 code indicates that the Powertrain Control Module (PCM) has detected a short to ground in the signal circuit of Fuel Temperature Sensor #2. This sensor, typically located on the fuel rail or return line, uses a thermistor to measure fuel temperature and adjust injection and evaporative strategies. A short to ground pulls the signal voltage near zero, which the PCM interprets as either extremely high temperature or an open circuit fault.
1. Commonly Affected Makes
2. Most Common Causes
- Internal short to ground in Fuel Temperature Sensor #2
- Signal wire (often light-colored or red) chafing against chassis or ground
- Damaged sensor connector with bent pins or corrosion bridging to ground
- Internal PCM failure (rare)
3. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy or rough idle
- Hard starting or extended crank time
4. Step-by-Step Diagnosis
Scan for codes and verify B1229 is present
Visually inspect Fuel Temperature Sensor #2 connector and wiring for damage or corrosion
Measure signal voltage at sensor connector with key on; should be around 0.5–4.5V; if near 0V, suspect short to ground
Disconnect sensor and check resistance between signal terminal and ground; infinite resistance indicates no short; low resistance confirms short to ground
If wiring and sensor check out, test PCM by backprobing signal pin at PCM connector
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, but you may experience reduced fuel economy and drivability issues. It's best to diagnose and repair promptly to avoid potential emissions or starting problems.
How much does it cost to fix?▼
Typically $150–$400, including diagnosis ($50–$100), sensor replacement ($30–$100), and labor ($70–$200). Wiring repairs may add $50–$150.