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Had to replace the CPS twice in the past two years? That’s not particularly normal. Could it be gone again for the same reason?
The CPS signal goes to the EZ ignition control module then to the fuel ECU. Even though the 2-1-4 code is set by the ECU (read on OBD port 2) and suggests a wiring fault between the ignition module and ECU, unless you’ve been touching that wiring or had other problems under the dash then more often than not it's still a problem with the CPS providing an intermittent or weak signal. The CPS cable is like coax with the ground as a foil shield to protect from signal loss or interference. That shield needs to make a good ground at both ends and be undamaged throughout it’s length to provide full shielding. An intermittent or weak signal could be a failed or possibly fouled sensor head, damaged wire in the cable (where you may or may not be able to see visible external damage), or a bad contact at the connector. I have not heard of fouling at the sensor tip, but I suppose it's possible.
Originally, there are one or two plastic standoff clips for the cable attached to the piping behind the block so there is no scuffing on the piping AND so that flexing from engine movement happens over a wide segment of wire between the firewall and the top clip. If the clips are missing then more flexing will happen down by the sensor head on the bellhousing which leads to premature failure of the wire there. I imagine one of the main differences between a Volvo CPS and a cheap aftermarket one is the quality of the wire in the cable. The standoffs often break or go missing after a few years. You can fashion your own standoffs using fat zip ties (black UV type will last longer) and a short bit of nylon/rubber hose/tube.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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