The P1670 trouble code is a diagnostic code that indicates a communication error between the Powertrain Control Module (PCM) and the Injector Driver Module (IDM) in certain vehicle models, particularly in Ford diesel engines. This code is often associated with starting issues and can be triggered by various electrical and mechanical problems within the engine management system.
| P1670 Code Meaning | P1670 Code Common Causes |
|---|---|
| Electronic Feedback Signal Not Detected | Faulty Injector Driver Module (IDM) |
| Communication Error between PCM and IDM | Damaged or corroded wiring harness |
| IDM Failure to Respond to PCM Commands | Blown fuses or faulty relays |
| Interruption in EF (Electronic Feedback) Circuit | Malfunctioning Powertrain Control Module (PCM) |
| FDCS (Fuel Delivery Command Signal) Issues | Loose or disconnected electrical connectors |
Faulty Injector Driver Module (IDM)
The Injector Driver Module is a crucial component in diesel engines, responsible for controlling the fuel injectors. When it fails, it can lead to the P1670 code and significant engine performance issues.
Symptoms
- Engine fails to start or hard starting
- Rough idle or stalling
- Reduced engine power
- Increased fuel consumption
- Check Engine Light illumination
Technical Explanation
The IDM receives signals from the PCM to control the timing and duration of fuel injection. When the IDM malfunctions, it cannot properly execute these commands or send feedback to the PCM, resulting in the P1670 code.
Step-by-step Diagnosis
- Connect an OBD-II scanner to verify the P1670 code.
- Check for any additional codes that may be present.
- Inspect the IDM for visible damage or corrosion.
- Test the IDM power supply and ground connections.
- Use a multimeter to check the resistance of the IDM circuits.
- Perform a voltage drop test on the IDM power and ground circuits.
Solution Methods
- Clean corrosion from IDM connections and ensure proper seating.
- Replace faulty wiring or connectors if found.
- If tests indicate a faulty IDM, replace the entire unit.
Cost Estimates
- IDM replacement: $300 – $800 (parts and labor)
- Diagnostic time: 1-2 hours at $75 – $150 per hour
Warning: IDM replacement should be performed by a qualified technician to ensure proper installation and calibration.
Damaged or Corroded Wiring Harness
Wiring issues are a common cause of the P1670 code, especially in older vehicles or those exposed to harsh environments.
Symptoms
- Intermittent starting problems
- Flickering dashboard lights
- Erratic engine behavior
- Multiple electrical issues across different systems
Technical Explanation
Corroded or damaged wires can interrupt the communication between the PCM and IDM. This can cause the EF signal to be lost or corrupted, triggering the P1670 code.
Step-by-step Diagnosis
- Visually inspect the wiring harness for signs of damage or corrosion.
- Check connectors for looseness or pin damage.
- Perform continuity tests on suspected wires.
- Use a voltage drop test to identify high-resistance connections.
- Inspect grounds for corrosion or looseness.
Solution Methods
- Clean corroded connections using electrical contact cleaner.
- Repair or replace damaged sections of the wiring harness.
- Apply dielectric grease to connections to prevent future corrosion.
- Replace entire harness if damage is extensive.
Cost Estimates
- Wire repair: $50 – $200
- Harness replacement: $200 – $1000 depending on vehicle model
Recommendation: Document all wire repairs and use proper automotive-grade wire and connectors for any replacements.
Blown Fuses or Faulty Relays
Electrical protection components like fuses and relays can fail, leading to power supply issues for the IDM or PCM.
Symptoms
- No-start condition
- Loss of power to specific systems
- Intermittent electrical issues
Technical Explanation
Fuses protect circuits from overcurrent situations, while relays control high-current circuits with low-current signals. Failure of either can interrupt the power supply to critical components involved in the P1670 code.
Step-by-step Diagnosis
- Locate the fuse box using the vehicle’s manual.
- Visually inspect fuses for signs of failure.
- Test suspect fuses with a multimeter for continuity.
- Locate and inspect relays related to the engine management system.
- Test relay function using a multimeter or by swapping with a known good relay.
Solution Methods
- Replace blown fuses with ones of the correct amperage.
- Clean relay sockets and ensure proper seating.
- Replace faulty relays.
- Investigate root cause of fuse or relay failure to prevent recurrence.
Cost Estimates
- Fuses: $1 – $10 each
- Relays: $10 – $50 each
- Diagnostic time: 0.5 – 1 hour
Warning: Never replace a blown fuse with one of a higher amperage rating, as this can lead to electrical fires.
Malfunctioning Powertrain Control Module (PCM)
While less common, PCM failure can cause the P1670 code by disrupting communication with the IDM.
Symptoms
- Multiple engine and transmission-related codes
- Erratic engine performance
- Failure of various vehicle systems
- No communication with diagnostic tools
Technical Explanation
The PCM is the brain of the engine management system. If it malfunctions, it may fail to send proper signals to the IDM or interpret the feedback correctly, resulting in the P1670 code.
Step-by-step Diagnosis
- Verify that all other potential causes have been ruled out.
- Check PCM power supply and ground connections.
- Inspect PCM for signs of physical damage or water intrusion.
- Attempt to communicate with the PCM using a professional-grade scan tool.
- Check for software updates or known issues for the specific vehicle model.
Solution Methods
- Repair damaged connections or wiring to the PCM.
- Update PCM software if available.
- Replace PCM if determined to be faulty.
- Perform necessary programming and learning procedures after replacement.
Cost Estimates
- PCM replacement: $500 – $2000 (parts and labor)
- Programming: $100 – $300
Recommendation: PCM replacement and programming should only be performed by experienced professionals with proper equipment.
Loose or Disconnected Electrical Connectors
Vibration, corrosion, or improper servicing can lead to loose or disconnected electrical connectors, causing intermittent issues and the P1670 code.
Symptoms
- Intermittent check engine light
- Sporadic engine performance issues
- Code clears and returns unpredictably
Technical Explanation
Loose connections can cause momentary interruptions in the communication between the PCM and IDM. These brief lapses can be enough to trigger the P1670 code.
Step-by-step Diagnosis
- Inspect all accessible connectors in the engine bay.
- Gently wiggle connectors while the engine is running to identify loose connections.
- Check for bent or pushed-out pins in connectors.
- Look for signs of water ingress or corrosion in connector housings.
- Perform pin drag tests to ensure proper tension.
Solution Methods
- Clean connectors with electrical contact cleaner.
- Reseat all relevant connectors, ensuring they click into place.
- Replace damaged connector housings or terminals.
- Apply dielectric grease to connections in high-moisture areas.
Cost Estimates
- DIY connector repair: $20 – $50 for materials
- Professional electrical repair: $100 – $300
Warning: Be gentle when working with electrical connectors to avoid damaging delicate pins or wires.
In conclusion, the P1670 code, while often associated with diesel engines, particularly Ford Powerstrokes, can be caused by a variety of electrical and mechanical issues. Proper diagnosis is crucial to avoid unnecessary parts replacement. Always start with the simplest and most common causes, such as checking fuses and inspecting wiring, before moving on to more complex components like the IDM or PCM. If you’re uncomfortable with electrical diagnostics or lack the proper tools, it’s best to seek the assistance of a qualified automotive technician. Remember that solving the P1670 code may require a combination of electrical knowledge, mechanical skill, and sometimes specialized diagnostic equipment.
Frequently Asked Questions About P1670
- Can I drive my vehicle with the P1670 code?
It’s not recommended to drive with this code active. The vehicle may run poorly or fail to start, potentially leaving you stranded. - How urgent is it to address the P1670 code?
This code should be addressed promptly. It can lead to no-start conditions and potential damage to fuel system components if ignored. - Will the P1670 code clear itself?
The code may clear temporarily if the issue is intermittent, but it will likely return unless the underlying problem is fixed. - Is the P1670 code specific to certain vehicle makes?
While common in Ford diesel engines, similar codes can appear in other makes. Always check your vehicle’s specific diagnostic information. - Can a bad battery cause the P1670 code?
A weak battery can cause various electrical issues, including communication errors. However, it’s less likely to be the sole cause of P1670. - How long does it take to diagnose and fix a P1670 code?
Diagnosis typically takes 1-2 hours. Repair time varies widely depending on the cause, from 30 minutes for a fuse replacement to several hours for an IDM or PCM replacement. - Are there any performance modifications that can trigger the P1670 code?
Some aftermarket performance modules or tuners can interfere with IDM-PCM communication. Always ensure compatibility with your vehicle’s systems. - Can extreme weather conditions contribute to the P1670 code?
Yes, extreme cold or heat can exacerbate existing electrical issues, potentially triggering the P1670 code in borderline cases.