What Does P1690 Mean?
The crankshaft position sensor signal from the fuel injection pump does not correlate with the primary CKP sensor monitored by the ECM. This indicates a synchronization error between the two sensors, typically found on diesel engines with mechanical injection pumps.
Safety Warning
Engine timing discrepancy can cause severe running issues, stalling, or potential internal engine damage. Do not drive until diagnosed.
Common Causes
35%
Injection pump CKP sensor failure or contamination
25%
Primary ECM CKP sensor intermittent signal
20%
Timing belt/chain slippage causing sensor misalignment
15%
Injection pump timing incorrectly set or mechanically shifted
5%
Wiring issues or interference affecting either sensor signal
Diagnostic Steps
1
Step 1: Compare CKP sensor signals from both ECM and injection pump using scan tool live data
2
Step 2: Inspect both CKP sensors for damage, debris, or excessive air gap (should be 0.020-0.040 inches)
3
Step 3: Verify injection pump timing marks alignment per manufacturer specifications
4
Step 4: Check timing belt/chain condition and verify proper tension and alignment
5
Step 5: Use oscilloscope to capture both CKP sensor waveforms simultaneously and compare phase relationship
Estimated Repair Cost
$400 - $2,500
Parts + labor, varies by vehicle and location
The crankshaft position sensor signal from the fuel injection pump does not correlate with the primary CKP sensor monitored by the ECM. This indicates a synchronization error between the two sensors, typically found on diesel engines with mechanical injection pumps.
The most common cause of P1690 (Fuel injection pump CKP Sensor Does Not Agree With ECM CKP Sensor) is: Injection pump CKP sensor failure or contamination
Typical repair costs for P1690 range from $400 to $2,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Engine timing discrepancy can cause severe running issues, stalling, or potential internal engine damage. Do not drive until diagnosed.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1690 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection System / Engine Timing
Difficulty
Type
Manufacturer
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