Expert: Roland Finston - 7/7/2009

Question
QUESTION: I have a 1997 Plymouth Grand Voyager Rallye. After taking in for 90,000 mile service, the "Service Engine Soon" light will come on periodically. Running the self-diagnostics produces a flashing MIL code of 45 and 21. What do these mean?

Thanks for your help.



ANSWER: Hi Rey,
The 21 says the oxygen sensor mounted on the exhaust manifold shows no changes in voltage as it should or is reading a high voltage which it shouldn't both of which suggests that it would be appropriate to check for broken/shorted wires at the sensor and if none are found then replace the sensor in any case.
The 45 code is not relevant to that vehicle as it is about the boost limit of a turbocharger set-up being exceeded. I can't explain why it should show up unless the PCM is from a different vehicle. Are you sure about count? If it were 55, that would be proper as it means 'end of readout'. I am also a bit surprised that you could get OBD-I codes on a '97 as that year was supposed to be cvonverted to the OBD-II 4-digit code system.
Roland

---------- FOLLOW-UP ----------

QUESTION: Roland,

Thanks for your reply.
The MIL codes are obtained by performing the multiple ON-OFF key procedure. Currently, the "Service Light" is not displaying , but the previous three times when it came on (since its service from last week), the same three MIL codes repeat. The first one is 12, which I know the meaning of from your previous posts (to others), then its a 45, 21 then 55, in that order. A 55, of course means what you had stated as "end of readout".

- Rey

Answer
Hi Rey,
I just found in a '96 manual for the Cirrus/Stratus that the 45 code means that there is a specific trans fault code stored in the memory of its controller. That you would have to get via an OBD-II reader plugged into the jack under the dash by the steering column. Ask for the code number and what it means. Then let me know. You can get a free readout at an Autozone parts store.
Roland