P0374 - Timing Reference High Resolution Signal A No Pulses
The PCM has detected a loss of the high resolution signal from the crankshaft position sensor (CKP) or camshaft position sensor (CMP). This signal is critical for engine timing and fuel injection synchronization. Without pulses, the PCM cannot determine engine position accurately, leading to a no-start or rough running condition.
1. Most Common Causes
- Faulty crankshaft position sensor
- Faulty camshaft position sensor
- Wiring or connector issues in the sensor circuit
- Damaged reluctor ring or tone wheel
- PCM failure (rare)
2. Symptoms You Will Notice
- Engine cranks but does not start
- Engine misfires or runs rough
- Check Engine Light illuminated
- Stalling or hesitation during acceleration
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect the CKP and CMP sensors and their wiring for damage or corrosion.
Step 3: Use a multimeter to check sensor resistance and voltage supply (typically 5V reference).
Step 4: Test sensor output with an oscilloscope while cranking to verify signal pattern.
Step 5: Check reluctor ring for damage or debris.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, the vehicle may stall or fail to start, posing a safety risk. It is recommended to have it towed to a repair shop.
How much does it cost to fix?▼
Typically $50-$150 for a sensor replacement, plus diagnostic fees. Labor costs vary by shop.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.