P0373: Erratic Timing Reference Signal A
The PCM has detected intermittent or erratic pulses from the high-resolution timing reference signal A, typically from the crankshaft position sensor. This signal is critical for engine timing and fuel injection synchronization. Intermittent pulses can be caused by a faulty sensor, damaged wiring, or a reluctor ring issue, leading to misfires and potential stalling.
1. Most Common Causes
- Faulty or worn crankshaft position (CKP) or camshaft position (CMP) sensor
- Damaged, corroded, or disconnected sensor wiring harness
- Electromagnetic interference in the signal circuit
- Damaged, misaligned, or broken reluctor ring teeth
- Internal ECM/PCM failure in signal processing
- Loose connections or excessive electrical resistance at the sensor connector
2. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire or rough idle
- Hard starting or no start
- Reduced power and fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect crankshaft position sensor wiring and connector for damage or corrosion.
Step 3: Test sensor resistance and AC voltage output while cranking (should produce a clean sine wave).
Step 4: Inspect reluctor ring for damage or debris through sensor hole or with a borescope.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with P0373 can cause stalling or no-start conditions, posing a safety risk. It's best to have it diagnosed and repaired immediately.
How much does it cost to fix?▼
Typically $50-$150 for a sensor replacement, but costs can be higher if wiring repairs or reluctor ring replacement is needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.